-- (c) The University of Glasgow 2006
-- (c) The GRASP/AQUA Project, Glasgow University, 1998
--
-- Type - public interface

{-# LANGUAGE CPP, FlexibleContexts #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}

-- | Main functions for manipulating types and type-related things
module Type (
        -- Note some of this is just re-exports from TyCon..

        -- * Main data types representing Types
        -- $type_classification

        -- $representation_types
        TyThing(..), Type, ArgFlag(..), AnonArgFlag(..), ForallVisFlag(..),
        KindOrType, PredType, ThetaType,
        Var, TyVar, isTyVar, TyCoVar, TyCoBinder, TyCoVarBinder, TyVarBinder,
        KnotTied,

        -- ** Constructing and deconstructing types
        mkTyVarTy, mkTyVarTys, getTyVar, getTyVar_maybe, repGetTyVar_maybe,
        getCastedTyVar_maybe, tyVarKind, varType,

        mkAppTy, mkAppTys, splitAppTy, splitAppTys, repSplitAppTys,
        splitAppTy_maybe, repSplitAppTy_maybe, tcRepSplitAppTy_maybe,

        mkVisFunTy, mkInvisFunTy, mkVisFunTys, mkInvisFunTys,
        splitFunTy, splitFunTy_maybe,
        splitFunTys, funResultTy, funArgTy,

        mkTyConApp, mkTyConTy,
        tyConAppTyCon_maybe, tyConAppTyConPicky_maybe,
        tyConAppArgs_maybe, tyConAppTyCon, tyConAppArgs,
        splitTyConApp_maybe, splitTyConApp, tyConAppArgN, nextRole,
        tcSplitTyConApp_maybe,
        splitListTyConApp_maybe,
        repSplitTyConApp_maybe,

        mkForAllTy, mkForAllTys, mkTyCoInvForAllTys,
        mkSpecForAllTy, mkSpecForAllTys,
        mkVisForAllTys, mkTyCoInvForAllTy,
        mkInvForAllTy, mkInvForAllTys,
        splitForAllTys, splitForAllTysSameVis,
        splitForAllVarBndrs,
        splitForAllTy_maybe, splitForAllTy,
        splitForAllTy_ty_maybe, splitForAllTy_co_maybe,
        splitPiTy_maybe, splitPiTy, splitPiTys,
        mkTyConBindersPreferAnon,
        mkPiTy, mkPiTys,
        mkLamType, mkLamTypes,
        piResultTy, piResultTys,
        applyTysX, dropForAlls,
        mkFamilyTyConApp,

        mkNumLitTy, isNumLitTy,
        mkStrLitTy, isStrLitTy,
        isLitTy,

        isPredTy,

        getRuntimeRep_maybe, kindRep_maybe, kindRep,

        mkCastTy, mkCoercionTy, splitCastTy_maybe,
        discardCast,

        userTypeError_maybe, pprUserTypeErrorTy,

        coAxNthLHS,
        stripCoercionTy,

        splitPiTysInvisible, splitPiTysInvisibleN,
        invisibleTyBndrCount,
        filterOutInvisibleTypes, filterOutInferredTypes,
        partitionInvisibleTypes, partitionInvisibles,
        tyConArgFlags, appTyArgFlags,
        synTyConResKind,

        modifyJoinResTy, setJoinResTy,

        -- ** Analyzing types
        TyCoMapper(..), mapType, mapCoercion,

        -- (Newtypes)
        newTyConInstRhs,

        -- ** Binders
        sameVis,
        mkTyCoVarBinder, mkTyCoVarBinders,
        mkTyVarBinders,
        mkAnonBinder,
        isAnonTyCoBinder,
        binderVar, binderVars, binderType, binderArgFlag,
        tyCoBinderType, tyCoBinderVar_maybe,
        tyBinderType,
        binderRelevantType_maybe,
        isVisibleArgFlag, isInvisibleArgFlag, isVisibleBinder,
        isInvisibleBinder, isNamedBinder,
        tyConBindersTyCoBinders,

        -- ** Common type constructors
        funTyCon,

        -- ** Predicates on types
        isTyVarTy, isFunTy, isCoercionTy,
        isCoercionTy_maybe, isForAllTy,
        isForAllTy_ty, isForAllTy_co,
        isPiTy, isTauTy, isFamFreeTy,
        isCoVarType,

        isValidJoinPointType,
        tyConAppNeedsKindSig,

        -- *** Levity and boxity
        isLiftedType_maybe,
        isLiftedTypeKind, isUnliftedTypeKind,
        isLiftedRuntimeRep, isUnliftedRuntimeRep,
        isUnliftedType, mightBeUnliftedType, isUnboxedTupleType, isUnboxedSumType,
        isAlgType, isDataFamilyAppType,
        isPrimitiveType, isStrictType,
        isRuntimeRepTy, isRuntimeRepVar, isRuntimeRepKindedTy,
        dropRuntimeRepArgs,
        getRuntimeRep,

        -- * Main data types representing Kinds
        Kind,

        -- ** Finding the kind of a type
        typeKind, tcTypeKind, isTypeLevPoly, resultIsLevPoly,
        tcIsLiftedTypeKind, tcIsConstraintKind, tcReturnsConstraintKind,
        tcIsRuntimeTypeKind,

        -- ** Common Kind
        liftedTypeKind,

        -- * Type free variables
        tyCoFVsOfType, tyCoFVsBndr, tyCoFVsVarBndr, tyCoFVsVarBndrs,
        tyCoVarsOfType, tyCoVarsOfTypes,
        tyCoVarsOfTypeDSet,
        coVarsOfType,
        coVarsOfTypes,
        closeOverKindsDSet, closeOverKindsFV, closeOverKindsList,
        closeOverKinds,

        noFreeVarsOfType,
        splitVisVarsOfType, splitVisVarsOfTypes,
        expandTypeSynonyms,
        typeSize, occCheckExpand,

        -- * Well-scoped lists of variables
        scopedSort, tyCoVarsOfTypeWellScoped,
        tyCoVarsOfTypesWellScoped,

        -- * Type comparison
        eqType, eqTypeX, eqTypes, nonDetCmpType, nonDetCmpTypes, nonDetCmpTypeX,
        nonDetCmpTypesX, nonDetCmpTc,
        eqVarBndrs,

        -- * Forcing evaluation of types
        seqType, seqTypes,

        -- * Other views onto Types
        coreView, tcView,

        tyConsOfType,

        -- * Main type substitution data types
        TvSubstEnv,     -- Representation widely visible
        TCvSubst(..),    -- Representation visible to a few friends

        -- ** Manipulating type substitutions
        emptyTvSubstEnv, emptyTCvSubst, mkEmptyTCvSubst,

        mkTCvSubst, zipTvSubst, mkTvSubstPrs,
        zipTCvSubst,
        notElemTCvSubst,
        getTvSubstEnv, setTvSubstEnv,
        zapTCvSubst, getTCvInScope, getTCvSubstRangeFVs,
        extendTCvInScope, extendTCvInScopeList, extendTCvInScopeSet,
        extendTCvSubst, extendCvSubst,
        extendTvSubst, extendTvSubstBinderAndInScope,
        extendTvSubstList, extendTvSubstAndInScope,
        extendTCvSubstList,
        extendTvSubstWithClone,
        extendTCvSubstWithClone,
        isInScope, composeTCvSubstEnv, composeTCvSubst, zipTyEnv, zipCoEnv,
        isEmptyTCvSubst, unionTCvSubst,

        -- ** Performing substitution on types and kinds
        substTy, substTys, substTyWith, substTysWith, substTheta,
        substTyAddInScope,
        substTyUnchecked, substTysUnchecked, substThetaUnchecked,
        substTyWithUnchecked,
        substCoUnchecked, substCoWithUnchecked,
        substTyVarBndr, substTyVarBndrs, substTyVar, substTyVars,
        substVarBndr, substVarBndrs,
        cloneTyVarBndr, cloneTyVarBndrs, lookupTyVar,

        -- * Tidying type related things up for printing
        tidyType,      tidyTypes,
        tidyOpenType,  tidyOpenTypes,
        tidyOpenKind,
        tidyVarBndr, tidyVarBndrs, tidyFreeTyCoVars,
        tidyOpenTyCoVar, tidyOpenTyCoVars,
        tidyTyCoVarOcc,
        tidyTopType,
        tidyKind,
        tidyTyCoVarBinder, tidyTyCoVarBinders,

        -- * Kinds
        isConstraintKindCon,
        classifiesTypeWithValues,
        isKindLevPoly
    ) where

#include "HsVersions.h"

import GhcPrelude

import BasicTypes

-- We import the representation and primitive functions from TyCoRep.
-- Many things are reexported, but not the representation!

import TyCoRep
import TyCoSubst
import TyCoTidy
import TyCoFVs

-- friends:
import Var
import VarEnv
import VarSet
import UniqSet

import TyCon
import TysPrim
import {-# SOURCE #-} TysWiredIn ( listTyCon, typeNatKind
                                 , typeSymbolKind, liftedTypeKind
                                 , constraintKind )
import PrelNames
import CoAxiom
import {-# SOURCE #-} Coercion( mkNomReflCo, mkGReflCo, mkReflCo
                              , mkTyConAppCo, mkAppCo, mkCoVarCo, mkAxiomRuleCo
                              , mkForAllCo, mkFunCo, mkAxiomInstCo, mkUnivCo
                              , mkSymCo, mkTransCo, mkNthCo, mkLRCo, mkInstCo
                              , mkKindCo, mkSubCo, mkFunCo, mkAxiomInstCo
                              , decomposePiCos, coercionKind, coercionType
                              , isReflexiveCo, seqCo )

-- others
import Util
import FV
import Outputable
import FastString
import Pair
import ListSetOps
import Unique ( nonDetCmpUnique )

import Maybes           ( orElse )
import Data.Maybe       ( isJust )
import Control.Monad    ( guard )

-- $type_classification
-- #type_classification#
--
-- Types are one of:
--
-- [Unboxed]            Iff its representation is other than a pointer
--                      Unboxed types are also unlifted.
--
-- [Lifted]             Iff it has bottom as an element.
--                      Closures always have lifted types: i.e. any
--                      let-bound identifier in Core must have a lifted
--                      type. Operationally, a lifted object is one that
--                      can be entered.
--                      Only lifted types may be unified with a type variable.
--
-- [Algebraic]          Iff it is a type with one or more constructors, whether
--                      declared with @data@ or @newtype@.
--                      An algebraic type is one that can be deconstructed
--                      with a case expression. This is /not/ the same as
--                      lifted types, because we also include unboxed
--                      tuples in this classification.
--
-- [Data]               Iff it is a type declared with @data@, or a boxed tuple.
--
-- [Primitive]          Iff it is a built-in type that can't be expressed in Haskell.
--
-- Currently, all primitive types are unlifted, but that's not necessarily
-- the case: for example, @Int@ could be primitive.
--
-- Some primitive types are unboxed, such as @Int#@, whereas some are boxed
-- but unlifted (such as @ByteArray#@).  The only primitive types that we
-- classify as algebraic are the unboxed tuples.
--
-- Some examples of type classifications that may make this a bit clearer are:
--
-- @
-- Type          primitive       boxed           lifted          algebraic
-- -----------------------------------------------------------------------------
-- Int#          Yes             No              No              No
-- ByteArray#    Yes             Yes             No              No
-- (\# a, b \#)  Yes             No              No              Yes
-- (\# a | b \#) Yes             No              No              Yes
-- (  a, b  )    No              Yes             Yes             Yes
-- [a]           No              Yes             Yes             Yes
-- @

-- $representation_types
-- A /source type/ is a type that is a separate type as far as the type checker is
-- concerned, but which has a more low-level representation as far as Core-to-Core
-- passes and the rest of the back end is concerned.
--
-- You don't normally have to worry about this, as the utility functions in
-- this module will automatically convert a source into a representation type
-- if they are spotted, to the best of its abilities. If you don't want this
-- to happen, use the equivalent functions from the "TcType" module.

{-
************************************************************************
*                                                                      *
                Type representation
*                                                                      *
************************************************************************

Note [coreView vs tcView]
~~~~~~~~~~~~~~~~~~~~~~~~~
So far as the typechecker is concerned, 'Constraint' and 'TYPE
LiftedRep' are distinct kinds.

But in Core these two are treated as identical.

We implement this by making 'coreView' convert 'Constraint' to 'TYPE
LiftedRep' on the fly.  The function tcView (used in the type checker)
does not do this.

See also #11715, which tracks removing this inconsistency.

-}

-- | Gives the typechecker view of a type. This unwraps synonyms but
-- leaves 'Constraint' alone. c.f. coreView, which turns Constraint into
-- TYPE LiftedRep. Returns Nothing if no unwrapping happens.
-- See also Note [coreView vs tcView]
{-# INLINE tcView #-}
tcView :: Type -> Maybe Type
tcView :: Type -> Maybe Type
tcView (TyConApp TyCon
tc [Type]
tys) | Just ([(TyVar, Type)]
tenv, Type
rhs, [Type]
tys') <- TyCon -> [Type] -> Maybe ([(TyVar, Type)], Type, [Type])
forall tyco.
TyCon -> [tyco] -> Maybe ([(TyVar, tyco)], Type, [tyco])
expandSynTyCon_maybe TyCon
tc [Type]
tys
  = Type -> Maybe Type
forall a. a -> Maybe a
Just (Type -> [Type] -> Type
mkAppTys (HasCallStack => TCvSubst -> Type -> Type
TCvSubst -> Type -> Type
substTy ([(TyVar, Type)] -> TCvSubst
mkTvSubstPrs [(TyVar, Type)]
tenv) Type
rhs) [Type]
tys')
               -- The free vars of 'rhs' should all be bound by 'tenv', so it's
               -- ok to use 'substTy' here.
               -- See also Note [The substitution invariant] in TyCoSubst.
               -- Its important to use mkAppTys, rather than (foldl AppTy),
               -- because the function part might well return a
               -- partially-applied type constructor; indeed, usually will!
tcView Type
_ = Maybe Type
forall a. Maybe a
Nothing

{-# INLINE coreView #-}
coreView :: Type -> Maybe Type
-- ^ This function Strips off the /top layer only/ of a type synonym
-- application (if any) its underlying representation type.
-- Returns Nothing if there is nothing to look through.
-- This function considers 'Constraint' to be a synonym of @TYPE LiftedRep@.
--
-- By being non-recursive and inlined, this case analysis gets efficiently
-- joined onto the case analysis that the caller is already doing
coreView :: Type -> Maybe Type
coreView ty :: Type
ty@(TyConApp TyCon
tc [Type]
tys)
  | Just ([(TyVar, Type)]
tenv, Type
rhs, [Type]
tys') <- TyCon -> [Type] -> Maybe ([(TyVar, Type)], Type, [Type])
forall tyco.
TyCon -> [tyco] -> Maybe ([(TyVar, tyco)], Type, [tyco])
expandSynTyCon_maybe TyCon
tc [Type]
tys
  = Type -> Maybe Type
forall a. a -> Maybe a
Just (Type -> [Type] -> Type
mkAppTys (HasCallStack => TCvSubst -> Type -> Type
TCvSubst -> Type -> Type
substTy ([(TyVar, Type)] -> TCvSubst
mkTvSubstPrs [(TyVar, Type)]
tenv) Type
rhs) [Type]
tys')
    -- This equation is exactly like tcView

  -- At the Core level, Constraint = Type
  -- See Note [coreView vs tcView]
  | TyCon -> Bool
isConstraintKindCon TyCon
tc
  = ASSERT2( null tys, ppr ty )
    Type -> Maybe Type
forall a. a -> Maybe a
Just Type
liftedTypeKind

coreView Type
_ = Maybe Type
forall a. Maybe a
Nothing

-----------------------------------------------
expandTypeSynonyms :: Type -> Type
-- ^ Expand out all type synonyms.  Actually, it'd suffice to expand out
-- just the ones that discard type variables (e.g.  type Funny a = Int)
-- But we don't know which those are currently, so we just expand all.
--
-- 'expandTypeSynonyms' only expands out type synonyms mentioned in the type,
-- not in the kinds of any TyCon or TyVar mentioned in the type.
--
-- Keep this synchronized with 'synonymTyConsOfType'
expandTypeSynonyms :: Type -> Type
expandTypeSynonyms Type
ty
  = TCvSubst -> Type -> Type
go (InScopeSet -> TCvSubst
mkEmptyTCvSubst InScopeSet
in_scope) Type
ty
  where
    in_scope :: InScopeSet
in_scope = VarSet -> InScopeSet
mkInScopeSet (Type -> VarSet
tyCoVarsOfType Type
ty)

    go :: TCvSubst -> Type -> Type
go TCvSubst
subst (TyConApp TyCon
tc [Type]
tys)
      | Just ([(TyVar, Type)]
tenv, Type
rhs, [Type]
tys') <- TyCon -> [Type] -> Maybe ([(TyVar, Type)], Type, [Type])
forall tyco.
TyCon -> [tyco] -> Maybe ([(TyVar, tyco)], Type, [tyco])
expandSynTyCon_maybe TyCon
tc [Type]
expanded_tys
      = let subst' :: TCvSubst
subst' = InScopeSet -> TvSubstEnv -> TCvSubst
mkTvSubst InScopeSet
in_scope ([(TyVar, Type)] -> TvSubstEnv
forall a. [(TyVar, a)] -> VarEnv a
mkVarEnv [(TyVar, Type)]
tenv)
            -- Make a fresh substitution; rhs has nothing to
            -- do with anything that has happened so far
            -- NB: if you make changes here, be sure to build an
            --     /idempotent/ substitution, even in the nested case
            --        type T a b = a -> b
            --        type S x y = T y x
            -- (#11665)
        in  Type -> [Type] -> Type
mkAppTys (TCvSubst -> Type -> Type
go TCvSubst
subst' Type
rhs) [Type]
tys'
      | Bool
otherwise
      = TyCon -> [Type] -> Type
TyConApp TyCon
tc [Type]
expanded_tys
      where
        expanded_tys :: [Type]
expanded_tys = ((Type -> Type) -> [Type] -> [Type]
forall a b. (a -> b) -> [a] -> [b]
map (TCvSubst -> Type -> Type
go TCvSubst
subst) [Type]
tys)

    go TCvSubst
_     (LitTy TyLit
l)     = TyLit -> Type
LitTy TyLit
l
    go TCvSubst
subst (TyVarTy TyVar
tv)  = TCvSubst -> TyVar -> Type
substTyVar TCvSubst
subst TyVar
tv
    go TCvSubst
subst (AppTy Type
t1 Type
t2) = Type -> Type -> Type
mkAppTy (TCvSubst -> Type -> Type
go TCvSubst
subst Type
t1) (TCvSubst -> Type -> Type
go TCvSubst
subst Type
t2)
    go TCvSubst
subst ty :: Type
ty@(FunTy AnonArgFlag
_ Type
arg Type
res)
      = Type
ty { ft_arg :: Type
ft_arg = TCvSubst -> Type -> Type
go TCvSubst
subst Type
arg, ft_res :: Type
ft_res = TCvSubst -> Type -> Type
go TCvSubst
subst Type
res }
    go TCvSubst
subst (ForAllTy (Bndr TyVar
tv ArgFlag
vis) Type
t)
      = let (TCvSubst
subst', TyVar
tv') = (TCvSubst -> Type -> Type)
-> TCvSubst -> TyVar -> (TCvSubst, TyVar)
substVarBndrUsing TCvSubst -> Type -> Type
go TCvSubst
subst TyVar
tv in
        VarBndr TyVar ArgFlag -> Type -> Type
ForAllTy (TyVar -> ArgFlag -> VarBndr TyVar ArgFlag
forall var argf. var -> argf -> VarBndr var argf
Bndr TyVar
tv' ArgFlag
vis) (TCvSubst -> Type -> Type
go TCvSubst
subst' Type
t)
    go TCvSubst
subst (CastTy Type
ty KindCoercion
co)  = Type -> KindCoercion -> Type
mkCastTy (TCvSubst -> Type -> Type
go TCvSubst
subst Type
ty) (TCvSubst -> KindCoercion -> KindCoercion
go_co TCvSubst
subst KindCoercion
co)
    go TCvSubst
subst (CoercionTy KindCoercion
co) = KindCoercion -> Type
mkCoercionTy (TCvSubst -> KindCoercion -> KindCoercion
go_co TCvSubst
subst KindCoercion
co)

    go_mco :: TCvSubst -> MCoercionN -> MCoercionN
go_mco TCvSubst
_     MCoercionN
MRefl    = MCoercionN
MRefl
    go_mco TCvSubst
subst (MCo KindCoercion
co) = KindCoercion -> MCoercionN
MCo (TCvSubst -> KindCoercion -> KindCoercion
go_co TCvSubst
subst KindCoercion
co)

    go_co :: TCvSubst -> KindCoercion -> KindCoercion
go_co TCvSubst
subst (Refl Type
ty)
      = Type -> KindCoercion
mkNomReflCo (TCvSubst -> Type -> Type
go TCvSubst
subst Type
ty)
    go_co TCvSubst
subst (GRefl Role
r Type
ty MCoercionN
mco)
      = Role -> Type -> MCoercionN -> KindCoercion
mkGReflCo Role
r (TCvSubst -> Type -> Type
go TCvSubst
subst Type
ty) (TCvSubst -> MCoercionN -> MCoercionN
go_mco TCvSubst
subst MCoercionN
mco)
       -- NB: coercions are always expanded upon creation
    go_co TCvSubst
subst (TyConAppCo Role
r TyCon
tc [KindCoercion]
args)
      = HasDebugCallStack =>
Role -> TyCon -> [KindCoercion] -> KindCoercion
Role -> TyCon -> [KindCoercion] -> KindCoercion
mkTyConAppCo Role
r TyCon
tc ((KindCoercion -> KindCoercion) -> [KindCoercion] -> [KindCoercion]
forall a b. (a -> b) -> [a] -> [b]
map (TCvSubst -> KindCoercion -> KindCoercion
go_co TCvSubst
subst) [KindCoercion]
args)
    go_co TCvSubst
subst (AppCo KindCoercion
co KindCoercion
arg)
      = KindCoercion -> KindCoercion -> KindCoercion
mkAppCo (TCvSubst -> KindCoercion -> KindCoercion
go_co TCvSubst
subst KindCoercion
co) (TCvSubst -> KindCoercion -> KindCoercion
go_co TCvSubst
subst KindCoercion
arg)
    go_co TCvSubst
subst (ForAllCo TyVar
tv KindCoercion
kind_co KindCoercion
co)
      = let (TCvSubst
subst', TyVar
tv', KindCoercion
kind_co') = TCvSubst
-> TyVar -> KindCoercion -> (TCvSubst, TyVar, KindCoercion)
go_cobndr TCvSubst
subst TyVar
tv KindCoercion
kind_co in
        TyVar -> KindCoercion -> KindCoercion -> KindCoercion
mkForAllCo TyVar
tv' KindCoercion
kind_co' (TCvSubst -> KindCoercion -> KindCoercion
go_co TCvSubst
subst' KindCoercion
co)
    go_co TCvSubst
subst (FunCo Role
r KindCoercion
co1 KindCoercion
co2)
      = Role -> KindCoercion -> KindCoercion -> KindCoercion
mkFunCo Role
r (TCvSubst -> KindCoercion -> KindCoercion
go_co TCvSubst
subst KindCoercion
co1) (TCvSubst -> KindCoercion -> KindCoercion
go_co TCvSubst
subst KindCoercion
co2)
    go_co TCvSubst
subst (CoVarCo TyVar
cv)
      = TCvSubst -> TyVar -> KindCoercion
substCoVar TCvSubst
subst TyVar
cv
    go_co TCvSubst
subst (AxiomInstCo CoAxiom Branched
ax Int
ind [KindCoercion]
args)
      = CoAxiom Branched -> Int -> [KindCoercion] -> KindCoercion
mkAxiomInstCo CoAxiom Branched
ax Int
ind ((KindCoercion -> KindCoercion) -> [KindCoercion] -> [KindCoercion]
forall a b. (a -> b) -> [a] -> [b]
map (TCvSubst -> KindCoercion -> KindCoercion
go_co TCvSubst
subst) [KindCoercion]
args)
    go_co TCvSubst
subst (UnivCo UnivCoProvenance
p Role
r Type
t1 Type
t2)
      = UnivCoProvenance -> Role -> Type -> Type -> KindCoercion
mkUnivCo (TCvSubst -> UnivCoProvenance -> UnivCoProvenance
go_prov TCvSubst
subst UnivCoProvenance
p) Role
r (TCvSubst -> Type -> Type
go TCvSubst
subst Type
t1) (TCvSubst -> Type -> Type
go TCvSubst
subst Type
t2)
    go_co TCvSubst
subst (SymCo KindCoercion
co)
      = KindCoercion -> KindCoercion
mkSymCo (TCvSubst -> KindCoercion -> KindCoercion
go_co TCvSubst
subst KindCoercion
co)
    go_co TCvSubst
subst (TransCo KindCoercion
co1 KindCoercion
co2)
      = KindCoercion -> KindCoercion -> KindCoercion
mkTransCo (TCvSubst -> KindCoercion -> KindCoercion
go_co TCvSubst
subst KindCoercion
co1) (TCvSubst -> KindCoercion -> KindCoercion
go_co TCvSubst
subst KindCoercion
co2)
    go_co TCvSubst
subst (NthCo Role
r Int
n KindCoercion
co)
      = HasDebugCallStack => Role -> Int -> KindCoercion -> KindCoercion
Role -> Int -> KindCoercion -> KindCoercion
mkNthCo Role
r Int
n (TCvSubst -> KindCoercion -> KindCoercion
go_co TCvSubst
subst KindCoercion
co)
    go_co TCvSubst
subst (LRCo LeftOrRight
lr KindCoercion
co)
      = LeftOrRight -> KindCoercion -> KindCoercion
mkLRCo LeftOrRight
lr (TCvSubst -> KindCoercion -> KindCoercion
go_co TCvSubst
subst KindCoercion
co)
    go_co TCvSubst
subst (InstCo KindCoercion
co KindCoercion
arg)
      = KindCoercion -> KindCoercion -> KindCoercion
mkInstCo (TCvSubst -> KindCoercion -> KindCoercion
go_co TCvSubst
subst KindCoercion
co) (TCvSubst -> KindCoercion -> KindCoercion
go_co TCvSubst
subst KindCoercion
arg)
    go_co TCvSubst
subst (KindCo KindCoercion
co)
      = KindCoercion -> KindCoercion
mkKindCo (TCvSubst -> KindCoercion -> KindCoercion
go_co TCvSubst
subst KindCoercion
co)
    go_co TCvSubst
subst (SubCo KindCoercion
co)
      = KindCoercion -> KindCoercion
mkSubCo (TCvSubst -> KindCoercion -> KindCoercion
go_co TCvSubst
subst KindCoercion
co)
    go_co TCvSubst
subst (AxiomRuleCo CoAxiomRule
ax [KindCoercion]
cs)
      = CoAxiomRule -> [KindCoercion] -> KindCoercion
AxiomRuleCo CoAxiomRule
ax ((KindCoercion -> KindCoercion) -> [KindCoercion] -> [KindCoercion]
forall a b. (a -> b) -> [a] -> [b]
map (TCvSubst -> KindCoercion -> KindCoercion
go_co TCvSubst
subst) [KindCoercion]
cs)
    go_co TCvSubst
_ (HoleCo CoercionHole
h)
      = String -> SDoc -> KindCoercion
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"expandTypeSynonyms hit a hole" (CoercionHole -> SDoc
forall a. Outputable a => a -> SDoc
ppr CoercionHole
h)

    go_prov :: TCvSubst -> UnivCoProvenance -> UnivCoProvenance
go_prov TCvSubst
_     UnivCoProvenance
UnsafeCoerceProv    = UnivCoProvenance
UnsafeCoerceProv
    go_prov TCvSubst
subst (PhantomProv KindCoercion
co)    = KindCoercion -> UnivCoProvenance
PhantomProv (TCvSubst -> KindCoercion -> KindCoercion
go_co TCvSubst
subst KindCoercion
co)
    go_prov TCvSubst
subst (ProofIrrelProv KindCoercion
co) = KindCoercion -> UnivCoProvenance
ProofIrrelProv (TCvSubst -> KindCoercion -> KindCoercion
go_co TCvSubst
subst KindCoercion
co)
    go_prov TCvSubst
_     p :: UnivCoProvenance
p@(PluginProv String
_)    = UnivCoProvenance
p

      -- the "False" and "const" are to accommodate the type of
      -- substForAllCoBndrUsing, which is general enough to
      -- handle coercion optimization (which sometimes swaps the
      -- order of a coercion)
    go_cobndr :: TCvSubst
-> TyVar -> KindCoercion -> (TCvSubst, TyVar, KindCoercion)
go_cobndr TCvSubst
subst = Bool
-> (KindCoercion -> KindCoercion)
-> TCvSubst
-> TyVar
-> KindCoercion
-> (TCvSubst, TyVar, KindCoercion)
substForAllCoBndrUsing Bool
False (TCvSubst -> KindCoercion -> KindCoercion
go_co TCvSubst
subst) TCvSubst
subst


-- | Extract the RuntimeRep classifier of a type from its kind. For example,
-- @kindRep * = LiftedRep@; Panics if this is not possible.
-- Treats * and Constraint as the same
kindRep :: HasDebugCallStack => Kind -> Type
kindRep :: Type -> Type
kindRep Type
k = case HasDebugCallStack => Type -> Maybe Type
Type -> Maybe Type
kindRep_maybe Type
k of
              Just Type
r  -> Type
r
              Maybe Type
Nothing -> String -> SDoc -> Type
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"kindRep" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
k)

-- | Given a kind (TYPE rr), extract its RuntimeRep classifier rr.
-- For example, @kindRep_maybe * = Just LiftedRep@
-- Returns 'Nothing' if the kind is not of form (TYPE rr)
-- Treats * and Constraint as the same
kindRep_maybe :: HasDebugCallStack => Kind -> Maybe Type
kindRep_maybe :: Type -> Maybe Type
kindRep_maybe Type
kind
  | Just Type
kind' <- Type -> Maybe Type
coreView Type
kind = HasDebugCallStack => Type -> Maybe Type
Type -> Maybe Type
kindRep_maybe Type
kind'
  | TyConApp TyCon
tc [Type
arg] <- Type
kind
  , TyCon
tc TyCon -> Unique -> Bool
forall a. Uniquable a => a -> Unique -> Bool
`hasKey` Unique
tYPETyConKey    = Type -> Maybe Type
forall a. a -> Maybe a
Just Type
arg
  | Bool
otherwise                   = Maybe Type
forall a. Maybe a
Nothing

-- | This version considers Constraint to be the same as *. Returns True
-- if the argument is equivalent to Type/Constraint and False otherwise.
-- See Note [Kind Constraint and kind Type]
isLiftedTypeKind :: Kind -> Bool
isLiftedTypeKind :: Type -> Bool
isLiftedTypeKind Type
kind
  = case HasDebugCallStack => Type -> Maybe Type
Type -> Maybe Type
kindRep_maybe Type
kind of
      Just Type
rep -> Type -> Bool
isLiftedRuntimeRep Type
rep
      Maybe Type
Nothing  -> Bool
False

isLiftedRuntimeRep :: Type -> Bool
-- isLiftedRuntimeRep is true of LiftedRep :: RuntimeRep
-- False of type variables (a :: RuntimeRep)
--   and of other reps e.g. (IntRep :: RuntimeRep)
isLiftedRuntimeRep :: Type -> Bool
isLiftedRuntimeRep Type
rep
  | Just Type
rep' <- Type -> Maybe Type
coreView Type
rep          = Type -> Bool
isLiftedRuntimeRep Type
rep'
  | TyConApp TyCon
rr_tc [Type]
args <- Type
rep
  , TyCon
rr_tc TyCon -> Unique -> Bool
forall a. Uniquable a => a -> Unique -> Bool
`hasKey` Unique
liftedRepDataConKey = ASSERT( null args ) True
  | Bool
otherwise                          = Bool
False

-- | Returns True if the kind classifies unlifted types and False otherwise.
-- Note that this returns False for levity-polymorphic kinds, which may
-- be specialized to a kind that classifies unlifted types.
isUnliftedTypeKind :: Kind -> Bool
isUnliftedTypeKind :: Type -> Bool
isUnliftedTypeKind Type
kind
  = case HasDebugCallStack => Type -> Maybe Type
Type -> Maybe Type
kindRep_maybe Type
kind of
      Just Type
rep -> Type -> Bool
isUnliftedRuntimeRep Type
rep
      Maybe Type
Nothing  -> Bool
False

isUnliftedRuntimeRep :: Type -> Bool
-- True of definitely-unlifted RuntimeReps
-- False of           (LiftedRep :: RuntimeRep)
--   and of variables (a :: RuntimeRep)
isUnliftedRuntimeRep :: Type -> Bool
isUnliftedRuntimeRep Type
rep
  | Just Type
rep' <- Type -> Maybe Type
coreView Type
rep = Type -> Bool
isUnliftedRuntimeRep Type
rep'
  | TyConApp TyCon
rr_tc [Type]
_ <- Type
rep   -- NB: args might be non-empty
                              --     e.g. TupleRep [r1, .., rn]
  = TyCon -> Bool
isPromotedDataCon TyCon
rr_tc Bool -> Bool -> Bool
&& Bool -> Bool
not (TyCon
rr_tc TyCon -> Unique -> Bool
forall a. Uniquable a => a -> Unique -> Bool
`hasKey` Unique
liftedRepDataConKey)
        -- Avoid searching all the unlifted RuntimeRep type cons
        -- In the RuntimeRep data type, only LiftedRep is lifted
        -- But be careful of type families (F tys) :: RuntimeRep
  | Bool
otherwise {- Variables, applications -}
  = Bool
False

-- | Is this the type 'RuntimeRep'?
isRuntimeRepTy :: Type -> Bool
isRuntimeRepTy :: Type -> Bool
isRuntimeRepTy Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Bool
isRuntimeRepTy Type
ty'
isRuntimeRepTy (TyConApp TyCon
tc [Type]
args)
  | TyCon
tc TyCon -> Unique -> Bool
forall a. Uniquable a => a -> Unique -> Bool
`hasKey` Unique
runtimeRepTyConKey = ASSERT( null args ) True
isRuntimeRepTy Type
_ = Bool
False

-- | Is a tyvar of type 'RuntimeRep'?
isRuntimeRepVar :: TyVar -> Bool
isRuntimeRepVar :: TyVar -> Bool
isRuntimeRepVar = Type -> Bool
isRuntimeRepTy (Type -> Bool) -> (TyVar -> Type) -> TyVar -> Bool
forall b c a. (b -> c) -> (a -> b) -> a -> c
. TyVar -> Type
tyVarKind


{-
************************************************************************
*                                                                      *
   Analyzing types
*                                                                      *
************************************************************************

These functions do a map-like operation over types, performing some operation
on all variables and binding sites. Primarily used for zonking.

Note [Efficiency for mapCoercion ForAllCo case]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
As noted in Note [Forall coercions] in TyCoRep, a ForAllCo is a bit redundant.
It stores a TyCoVar and a Coercion, where the kind of the TyCoVar always matches
the left-hand kind of the coercion. This is convenient lots of the time, but
not when mapping a function over a coercion.

The problem is that tcm_tybinder will affect the TyCoVar's kind and
mapCoercion will affect the Coercion, and we hope that the results will be
the same. Even if they are the same (which should generally happen with
correct algorithms), then there is an efficiency issue. In particular,
this problem seems to make what should be a linear algorithm into a potentially
exponential one. But it's only going to be bad in the case where there's
lots of foralls in the kinds of other foralls. Like this:

  forall a : (forall b : (forall c : ...). ...). ...

This construction seems unlikely. So we'll do the inefficient, easy way
for now.

Note [Specialising mappers]
~~~~~~~~~~~~~~~~~~~~~~~~~~~
These INLINABLE pragmas are indispensable. mapType/mapCoercion are used
to implement zonking, and it's vital that they get specialised to the TcM
monad. This specialisation happens automatically (that is, without a
SPECIALISE pragma) as long as the definitions are INLINABLE. For example,
this one change made a 20% allocation difference in perf/compiler/T5030.

-}

-- | This describes how a "map" operation over a type/coercion should behave
data TyCoMapper env m
  = TyCoMapper
      { TyCoMapper env m -> env -> TyVar -> m Type
tcm_tyvar :: env -> TyVar -> m Type
      , TyCoMapper env m -> env -> TyVar -> m KindCoercion
tcm_covar :: env -> CoVar -> m Coercion
      , TyCoMapper env m -> env -> CoercionHole -> m KindCoercion
tcm_hole  :: env -> CoercionHole -> m Coercion
          -- ^ What to do with coercion holes.
          -- See Note [Coercion holes] in TyCoRep.

      , TyCoMapper env m -> env -> TyVar -> ArgFlag -> m (env, TyVar)
tcm_tycobinder :: env -> TyCoVar -> ArgFlag -> m (env, TyCoVar)
          -- ^ The returned env is used in the extended scope

      , TyCoMapper env m -> TyCon -> m TyCon
tcm_tycon :: TyCon -> m TyCon
          -- ^ This is used only for TcTyCons
          -- a) To zonk TcTyCons
          -- b) To turn TcTyCons into TyCons.
          --    See Note [Type checking recursive type and class declarations]
          --    in TcTyClsDecls
      }

{-# INLINABLE mapType #-}  -- See Note [Specialising mappers]
mapType :: Monad m => TyCoMapper env m -> env -> Type -> m Type
mapType :: TyCoMapper env m -> env -> Type -> m Type
mapType mapper :: TyCoMapper env m
mapper@(TyCoMapper { tcm_tyvar :: forall env (m :: * -> *).
TyCoMapper env m -> env -> TyVar -> m Type
tcm_tyvar = env -> TyVar -> m Type
tyvar
                           , tcm_tycobinder :: forall env (m :: * -> *).
TyCoMapper env m -> env -> TyVar -> ArgFlag -> m (env, TyVar)
tcm_tycobinder = env -> TyVar -> ArgFlag -> m (env, TyVar)
tycobinder
                           , tcm_tycon :: forall env (m :: * -> *). TyCoMapper env m -> TyCon -> m TyCon
tcm_tycon = TyCon -> m TyCon
tycon })
        env
env Type
ty
  = Type -> m Type
go Type
ty
  where
    go :: Type -> m Type
go (TyVarTy TyVar
tv)    = env -> TyVar -> m Type
tyvar env
env TyVar
tv
    go (AppTy Type
t1 Type
t2)   = Type -> Type -> Type
mkAppTy (Type -> Type -> Type) -> m Type -> m (Type -> Type)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> Type -> m Type
go Type
t1 m (Type -> Type) -> m Type -> m Type
forall (f :: * -> *) a b. Applicative f => f (a -> b) -> f a -> f b
<*> Type -> m Type
go Type
t2
    go ty :: Type
ty@(LitTy {})   = Type -> m Type
forall (m :: * -> *) a. Monad m => a -> m a
return Type
ty
    go (CastTy Type
ty KindCoercion
co)  = Type -> KindCoercion -> Type
mkCastTy (Type -> KindCoercion -> Type)
-> m Type -> m (KindCoercion -> Type)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> Type -> m Type
go Type
ty m (KindCoercion -> Type) -> m KindCoercion -> m Type
forall (f :: * -> *) a b. Applicative f => f (a -> b) -> f a -> f b
<*> TyCoMapper env m -> env -> KindCoercion -> m KindCoercion
forall (m :: * -> *) env.
Monad m =>
TyCoMapper env m -> env -> KindCoercion -> m KindCoercion
mapCoercion TyCoMapper env m
mapper env
env KindCoercion
co
    go (CoercionTy KindCoercion
co) = KindCoercion -> Type
CoercionTy (KindCoercion -> Type) -> m KindCoercion -> m Type
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> TyCoMapper env m -> env -> KindCoercion -> m KindCoercion
forall (m :: * -> *) env.
Monad m =>
TyCoMapper env m -> env -> KindCoercion -> m KindCoercion
mapCoercion TyCoMapper env m
mapper env
env KindCoercion
co

    go ty :: Type
ty@(FunTy AnonArgFlag
_ Type
arg Type
res)
      = do { Type
arg' <- Type -> m Type
go Type
arg; Type
res' <- Type -> m Type
go Type
res
           ; Type -> m Type
forall (m :: * -> *) a. Monad m => a -> m a
return (Type
ty { ft_arg :: Type
ft_arg = Type
arg', ft_res :: Type
ft_res = Type
res' }) }

    go ty :: Type
ty@(TyConApp TyCon
tc [Type]
tys)
      | TyCon -> Bool
isTcTyCon TyCon
tc
      = do { TyCon
tc' <- TyCon -> m TyCon
tycon TyCon
tc
           ; TyCon -> [Type] -> Type
mkTyConApp TyCon
tc' ([Type] -> Type) -> m [Type] -> m Type
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> (Type -> m Type) -> [Type] -> m [Type]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM Type -> m Type
go [Type]
tys }

      -- Not a TcTyCon
      | [Type] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [Type]
tys    -- Avoid allocation in this very
      = Type -> m Type
forall (m :: * -> *) a. Monad m => a -> m a
return Type
ty   -- common case (E.g. Int, LiftedRep etc)

      | Bool
otherwise
      = TyCon -> [Type] -> Type
mkTyConApp TyCon
tc ([Type] -> Type) -> m [Type] -> m Type
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> (Type -> m Type) -> [Type] -> m [Type]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM Type -> m Type
go [Type]
tys

    go (ForAllTy (Bndr TyVar
tv ArgFlag
vis) Type
inner)
      = do { (env
env', TyVar
tv') <- env -> TyVar -> ArgFlag -> m (env, TyVar)
tycobinder env
env TyVar
tv ArgFlag
vis
           ; Type
inner' <- TyCoMapper env m -> env -> Type -> m Type
forall (m :: * -> *) env.
Monad m =>
TyCoMapper env m -> env -> Type -> m Type
mapType TyCoMapper env m
mapper env
env' Type
inner
           ; Type -> m Type
forall (m :: * -> *) a. Monad m => a -> m a
return (Type -> m Type) -> Type -> m Type
forall a b. (a -> b) -> a -> b
$ VarBndr TyVar ArgFlag -> Type -> Type
ForAllTy (TyVar -> ArgFlag -> VarBndr TyVar ArgFlag
forall var argf. var -> argf -> VarBndr var argf
Bndr TyVar
tv' ArgFlag
vis) Type
inner' }

{-# INLINABLE mapCoercion #-}  -- See Note [Specialising mappers]
mapCoercion :: Monad m
            => TyCoMapper env m -> env -> Coercion -> m Coercion
mapCoercion :: TyCoMapper env m -> env -> KindCoercion -> m KindCoercion
mapCoercion mapper :: TyCoMapper env m
mapper@(TyCoMapper { tcm_covar :: forall env (m :: * -> *).
TyCoMapper env m -> env -> TyVar -> m KindCoercion
tcm_covar = env -> TyVar -> m KindCoercion
covar
                               , tcm_hole :: forall env (m :: * -> *).
TyCoMapper env m -> env -> CoercionHole -> m KindCoercion
tcm_hole = env -> CoercionHole -> m KindCoercion
cohole
                               , tcm_tycobinder :: forall env (m :: * -> *).
TyCoMapper env m -> env -> TyVar -> ArgFlag -> m (env, TyVar)
tcm_tycobinder = env -> TyVar -> ArgFlag -> m (env, TyVar)
tycobinder
                               , tcm_tycon :: forall env (m :: * -> *). TyCoMapper env m -> TyCon -> m TyCon
tcm_tycon = TyCon -> m TyCon
tycon })
            env
env KindCoercion
co
  = KindCoercion -> m KindCoercion
go KindCoercion
co
  where
    go_mco :: MCoercionN -> m MCoercionN
go_mco MCoercionN
MRefl    = MCoercionN -> m MCoercionN
forall (m :: * -> *) a. Monad m => a -> m a
return MCoercionN
MRefl
    go_mco (MCo KindCoercion
co) = KindCoercion -> MCoercionN
MCo (KindCoercion -> MCoercionN) -> m KindCoercion -> m MCoercionN
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> (KindCoercion -> m KindCoercion
go KindCoercion
co)

    go :: KindCoercion -> m KindCoercion
go (Refl Type
ty) = Type -> KindCoercion
Refl (Type -> KindCoercion) -> m Type -> m KindCoercion
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> TyCoMapper env m -> env -> Type -> m Type
forall (m :: * -> *) env.
Monad m =>
TyCoMapper env m -> env -> Type -> m Type
mapType TyCoMapper env m
mapper env
env Type
ty
    go (GRefl Role
r Type
ty MCoercionN
mco) = Role -> Type -> MCoercionN -> KindCoercion
mkGReflCo Role
r (Type -> MCoercionN -> KindCoercion)
-> m Type -> m (MCoercionN -> KindCoercion)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> TyCoMapper env m -> env -> Type -> m Type
forall (m :: * -> *) env.
Monad m =>
TyCoMapper env m -> env -> Type -> m Type
mapType TyCoMapper env m
mapper env
env Type
ty m (MCoercionN -> KindCoercion) -> m MCoercionN -> m KindCoercion
forall (f :: * -> *) a b. Applicative f => f (a -> b) -> f a -> f b
<*> (MCoercionN -> m MCoercionN
go_mco MCoercionN
mco)
    go (TyConAppCo Role
r TyCon
tc [KindCoercion]
args)
      = do { TyCon
tc' <- if TyCon -> Bool
isTcTyCon TyCon
tc
                    then TyCon -> m TyCon
tycon TyCon
tc
                    else TyCon -> m TyCon
forall (m :: * -> *) a. Monad m => a -> m a
return TyCon
tc
           ; HasDebugCallStack =>
Role -> TyCon -> [KindCoercion] -> KindCoercion
Role -> TyCon -> [KindCoercion] -> KindCoercion
mkTyConAppCo Role
r TyCon
tc' ([KindCoercion] -> KindCoercion)
-> m [KindCoercion] -> m KindCoercion
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> (KindCoercion -> m KindCoercion)
-> [KindCoercion] -> m [KindCoercion]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM KindCoercion -> m KindCoercion
go [KindCoercion]
args }
    go (AppCo KindCoercion
c1 KindCoercion
c2) = KindCoercion -> KindCoercion -> KindCoercion
mkAppCo (KindCoercion -> KindCoercion -> KindCoercion)
-> m KindCoercion -> m (KindCoercion -> KindCoercion)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> KindCoercion -> m KindCoercion
go KindCoercion
c1 m (KindCoercion -> KindCoercion)
-> m KindCoercion -> m KindCoercion
forall (f :: * -> *) a b. Applicative f => f (a -> b) -> f a -> f b
<*> KindCoercion -> m KindCoercion
go KindCoercion
c2
    go (ForAllCo TyVar
tv KindCoercion
kind_co KindCoercion
co)
      = do { KindCoercion
kind_co' <- KindCoercion -> m KindCoercion
go KindCoercion
kind_co
           ; (env
env', TyVar
tv') <- env -> TyVar -> ArgFlag -> m (env, TyVar)
tycobinder env
env TyVar
tv ArgFlag
Inferred
           ; KindCoercion
co' <- TyCoMapper env m -> env -> KindCoercion -> m KindCoercion
forall (m :: * -> *) env.
Monad m =>
TyCoMapper env m -> env -> KindCoercion -> m KindCoercion
mapCoercion TyCoMapper env m
mapper env
env' KindCoercion
co
           ; KindCoercion -> m KindCoercion
forall (m :: * -> *) a. Monad m => a -> m a
return (KindCoercion -> m KindCoercion) -> KindCoercion -> m KindCoercion
forall a b. (a -> b) -> a -> b
$ TyVar -> KindCoercion -> KindCoercion -> KindCoercion
mkForAllCo TyVar
tv' KindCoercion
kind_co' KindCoercion
co' }
        -- See Note [Efficiency for mapCoercion ForAllCo case]
    go (FunCo Role
r KindCoercion
c1 KindCoercion
c2) = Role -> KindCoercion -> KindCoercion -> KindCoercion
mkFunCo Role
r (KindCoercion -> KindCoercion -> KindCoercion)
-> m KindCoercion -> m (KindCoercion -> KindCoercion)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> KindCoercion -> m KindCoercion
go KindCoercion
c1 m (KindCoercion -> KindCoercion)
-> m KindCoercion -> m KindCoercion
forall (f :: * -> *) a b. Applicative f => f (a -> b) -> f a -> f b
<*> KindCoercion -> m KindCoercion
go KindCoercion
c2
    go (CoVarCo TyVar
cv) = env -> TyVar -> m KindCoercion
covar env
env TyVar
cv
    go (AxiomInstCo CoAxiom Branched
ax Int
i [KindCoercion]
args)
      = CoAxiom Branched -> Int -> [KindCoercion] -> KindCoercion
mkAxiomInstCo CoAxiom Branched
ax Int
i ([KindCoercion] -> KindCoercion)
-> m [KindCoercion] -> m KindCoercion
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> (KindCoercion -> m KindCoercion)
-> [KindCoercion] -> m [KindCoercion]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM KindCoercion -> m KindCoercion
go [KindCoercion]
args
    go (HoleCo CoercionHole
hole) = env -> CoercionHole -> m KindCoercion
cohole env
env CoercionHole
hole
    go (UnivCo UnivCoProvenance
p Role
r Type
t1 Type
t2)
      = UnivCoProvenance -> Role -> Type -> Type -> KindCoercion
mkUnivCo (UnivCoProvenance -> Role -> Type -> Type -> KindCoercion)
-> m UnivCoProvenance -> m (Role -> Type -> Type -> KindCoercion)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> UnivCoProvenance -> m UnivCoProvenance
go_prov UnivCoProvenance
p m (Role -> Type -> Type -> KindCoercion)
-> m Role -> m (Type -> Type -> KindCoercion)
forall (f :: * -> *) a b. Applicative f => f (a -> b) -> f a -> f b
<*> Role -> m Role
forall (f :: * -> *) a. Applicative f => a -> f a
pure Role
r
                 m (Type -> Type -> KindCoercion)
-> m Type -> m (Type -> KindCoercion)
forall (f :: * -> *) a b. Applicative f => f (a -> b) -> f a -> f b
<*> TyCoMapper env m -> env -> Type -> m Type
forall (m :: * -> *) env.
Monad m =>
TyCoMapper env m -> env -> Type -> m Type
mapType TyCoMapper env m
mapper env
env Type
t1 m (Type -> KindCoercion) -> m Type -> m KindCoercion
forall (f :: * -> *) a b. Applicative f => f (a -> b) -> f a -> f b
<*> TyCoMapper env m -> env -> Type -> m Type
forall (m :: * -> *) env.
Monad m =>
TyCoMapper env m -> env -> Type -> m Type
mapType TyCoMapper env m
mapper env
env Type
t2
    go (SymCo KindCoercion
co) = KindCoercion -> KindCoercion
mkSymCo (KindCoercion -> KindCoercion) -> m KindCoercion -> m KindCoercion
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> KindCoercion -> m KindCoercion
go KindCoercion
co
    go (TransCo KindCoercion
c1 KindCoercion
c2) = KindCoercion -> KindCoercion -> KindCoercion
mkTransCo (KindCoercion -> KindCoercion -> KindCoercion)
-> m KindCoercion -> m (KindCoercion -> KindCoercion)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> KindCoercion -> m KindCoercion
go KindCoercion
c1 m (KindCoercion -> KindCoercion)
-> m KindCoercion -> m KindCoercion
forall (f :: * -> *) a b. Applicative f => f (a -> b) -> f a -> f b
<*> KindCoercion -> m KindCoercion
go KindCoercion
c2
    go (AxiomRuleCo CoAxiomRule
r [KindCoercion]
cos) = CoAxiomRule -> [KindCoercion] -> KindCoercion
AxiomRuleCo CoAxiomRule
r ([KindCoercion] -> KindCoercion)
-> m [KindCoercion] -> m KindCoercion
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> (KindCoercion -> m KindCoercion)
-> [KindCoercion] -> m [KindCoercion]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM KindCoercion -> m KindCoercion
go [KindCoercion]
cos
    go (NthCo Role
r Int
i KindCoercion
co)      = HasDebugCallStack => Role -> Int -> KindCoercion -> KindCoercion
Role -> Int -> KindCoercion -> KindCoercion
mkNthCo Role
r Int
i (KindCoercion -> KindCoercion) -> m KindCoercion -> m KindCoercion
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> KindCoercion -> m KindCoercion
go KindCoercion
co
    go (LRCo LeftOrRight
lr KindCoercion
co)        = LeftOrRight -> KindCoercion -> KindCoercion
mkLRCo LeftOrRight
lr (KindCoercion -> KindCoercion) -> m KindCoercion -> m KindCoercion
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> KindCoercion -> m KindCoercion
go KindCoercion
co
    go (InstCo KindCoercion
co KindCoercion
arg)     = KindCoercion -> KindCoercion -> KindCoercion
mkInstCo (KindCoercion -> KindCoercion -> KindCoercion)
-> m KindCoercion -> m (KindCoercion -> KindCoercion)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> KindCoercion -> m KindCoercion
go KindCoercion
co m (KindCoercion -> KindCoercion)
-> m KindCoercion -> m KindCoercion
forall (f :: * -> *) a b. Applicative f => f (a -> b) -> f a -> f b
<*> KindCoercion -> m KindCoercion
go KindCoercion
arg
    go (KindCo KindCoercion
co)         = KindCoercion -> KindCoercion
mkKindCo (KindCoercion -> KindCoercion) -> m KindCoercion -> m KindCoercion
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> KindCoercion -> m KindCoercion
go KindCoercion
co
    go (SubCo KindCoercion
co)          = KindCoercion -> KindCoercion
mkSubCo (KindCoercion -> KindCoercion) -> m KindCoercion -> m KindCoercion
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> KindCoercion -> m KindCoercion
go KindCoercion
co

    go_prov :: UnivCoProvenance -> m UnivCoProvenance
go_prov UnivCoProvenance
UnsafeCoerceProv    = UnivCoProvenance -> m UnivCoProvenance
forall (m :: * -> *) a. Monad m => a -> m a
return UnivCoProvenance
UnsafeCoerceProv
    go_prov (PhantomProv KindCoercion
co)    = KindCoercion -> UnivCoProvenance
PhantomProv (KindCoercion -> UnivCoProvenance)
-> m KindCoercion -> m UnivCoProvenance
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> KindCoercion -> m KindCoercion
go KindCoercion
co
    go_prov (ProofIrrelProv KindCoercion
co) = KindCoercion -> UnivCoProvenance
ProofIrrelProv (KindCoercion -> UnivCoProvenance)
-> m KindCoercion -> m UnivCoProvenance
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> KindCoercion -> m KindCoercion
go KindCoercion
co
    go_prov p :: UnivCoProvenance
p@(PluginProv String
_)    = UnivCoProvenance -> m UnivCoProvenance
forall (m :: * -> *) a. Monad m => a -> m a
return UnivCoProvenance
p

{-
************************************************************************
*                                                                      *
\subsection{Constructor-specific functions}
*                                                                      *
************************************************************************


---------------------------------------------------------------------
                                TyVarTy
                                ~~~~~~~
-}

-- | Attempts to obtain the type variable underlying a 'Type', and panics with the
-- given message if this is not a type variable type. See also 'getTyVar_maybe'
getTyVar :: String -> Type -> TyVar
getTyVar :: String -> Type -> TyVar
getTyVar String
msg Type
ty = case Type -> Maybe TyVar
getTyVar_maybe Type
ty of
                    Just TyVar
tv -> TyVar
tv
                    Maybe TyVar
Nothing -> String -> TyVar
forall a. String -> a
panic (String
"getTyVar: " String -> String -> String
forall a. [a] -> [a] -> [a]
++ String
msg)

isTyVarTy :: Type -> Bool
isTyVarTy :: Type -> Bool
isTyVarTy Type
ty = Maybe TyVar -> Bool
forall a. Maybe a -> Bool
isJust (Type -> Maybe TyVar
getTyVar_maybe Type
ty)

-- | Attempts to obtain the type variable underlying a 'Type'
getTyVar_maybe :: Type -> Maybe TyVar
getTyVar_maybe :: Type -> Maybe TyVar
getTyVar_maybe Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Maybe TyVar
getTyVar_maybe Type
ty'
                  | Bool
otherwise               = Type -> Maybe TyVar
repGetTyVar_maybe Type
ty

-- | If the type is a tyvar, possibly under a cast, returns it, along
-- with the coercion. Thus, the co is :: kind tv ~N kind ty
getCastedTyVar_maybe :: Type -> Maybe (TyVar, CoercionN)
getCastedTyVar_maybe :: Type -> Maybe (TyVar, KindCoercion)
getCastedTyVar_maybe Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Maybe (TyVar, KindCoercion)
getCastedTyVar_maybe Type
ty'
getCastedTyVar_maybe (CastTy (TyVarTy TyVar
tv) KindCoercion
co)     = (TyVar, KindCoercion) -> Maybe (TyVar, KindCoercion)
forall a. a -> Maybe a
Just (TyVar
tv, KindCoercion
co)
getCastedTyVar_maybe (TyVarTy TyVar
tv)
  = (TyVar, KindCoercion) -> Maybe (TyVar, KindCoercion)
forall a. a -> Maybe a
Just (TyVar
tv, Role -> Type -> KindCoercion
mkReflCo Role
Nominal (TyVar -> Type
tyVarKind TyVar
tv))
getCastedTyVar_maybe Type
_                            = Maybe (TyVar, KindCoercion)
forall a. Maybe a
Nothing

-- | Attempts to obtain the type variable underlying a 'Type', without
-- any expansion
repGetTyVar_maybe :: Type -> Maybe TyVar
repGetTyVar_maybe :: Type -> Maybe TyVar
repGetTyVar_maybe (TyVarTy TyVar
tv) = TyVar -> Maybe TyVar
forall a. a -> Maybe a
Just TyVar
tv
repGetTyVar_maybe Type
_            = Maybe TyVar
forall a. Maybe a
Nothing

{-
---------------------------------------------------------------------
                                AppTy
                                ~~~~~
We need to be pretty careful with AppTy to make sure we obey the
invariant that a TyConApp is always visibly so.  mkAppTy maintains the
invariant: use it.

Note [Decomposing fat arrow c=>t]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Can we unify (a b) with (Eq a => ty)?   If we do so, we end up with
a partial application like ((=>) Eq a) which doesn't make sense in
source Haskell.  In contrast, we *can* unify (a b) with (t1 -> t2).
Here's an example (#9858) of how you might do it:
   i :: (Typeable a, Typeable b) => Proxy (a b) -> TypeRep
   i p = typeRep p

   j = i (Proxy :: Proxy (Eq Int => Int))
The type (Proxy (Eq Int => Int)) is only accepted with -XImpredicativeTypes,
but suppose we want that.  But then in the call to 'i', we end
up decomposing (Eq Int => Int), and we definitely don't want that.

This really only applies to the type checker; in Core, '=>' and '->'
are the same, as are 'Constraint' and '*'.  But for now I've put
the test in repSplitAppTy_maybe, which applies throughout, because
the other calls to splitAppTy are in Unify, which is also used by
the type checker (e.g. when matching type-function equations).

-}

-- | Applies a type to another, as in e.g. @k a@
mkAppTy :: Type -> Type -> Type
  -- See Note [Respecting definitional equality], invariant (EQ1).
mkAppTy :: Type -> Type -> Type
mkAppTy (CastTy Type
fun_ty KindCoercion
co) Type
arg_ty
  | ([KindCoercion
arg_co], KindCoercion
res_co) <- HasDebugCallStack =>
KindCoercion
-> Pair Type -> [Type] -> ([KindCoercion], KindCoercion)
KindCoercion
-> Pair Type -> [Type] -> ([KindCoercion], KindCoercion)
decomposePiCos KindCoercion
co (KindCoercion -> Pair Type
coercionKind KindCoercion
co) [Type
arg_ty]
  = (Type
fun_ty Type -> Type -> Type
`mkAppTy` (Type
arg_ty Type -> KindCoercion -> Type
`mkCastTy` KindCoercion
arg_co)) Type -> KindCoercion -> Type
`mkCastTy` KindCoercion
res_co

mkAppTy (TyConApp TyCon
tc [Type]
tys) Type
ty2 = TyCon -> [Type] -> Type
mkTyConApp TyCon
tc ([Type]
tys [Type] -> [Type] -> [Type]
forall a. [a] -> [a] -> [a]
++ [Type
ty2])
mkAppTy Type
ty1               Type
ty2 = Type -> Type -> Type
AppTy Type
ty1 Type
ty2
        -- Note that the TyConApp could be an
        -- under-saturated type synonym.  GHC allows that; e.g.
        --      type Foo k = k a -> k a
        --      type Id x = x
        --      foo :: Foo Id -> Foo Id
        --
        -- Here Id is partially applied in the type sig for Foo,
        -- but once the type synonyms are expanded all is well
        --
        -- Moreover in TcHsTypes.tcInferApps we build up a type
        --   (T t1 t2 t3) one argument at a type, thus forming
        --   (T t1), (T t1 t2), etc

mkAppTys :: Type -> [Type] -> Type
mkAppTys :: Type -> [Type] -> Type
mkAppTys Type
ty1                []   = Type
ty1
mkAppTys (CastTy Type
fun_ty KindCoercion
co) [Type]
arg_tys  -- much more efficient then nested mkAppTy
                                     -- Why do this? See (EQ1) of
                                     -- Note [Respecting definitional equality]
                                     -- in TyCoRep
  = (Type -> Type -> Type) -> Type -> [Type] -> Type
forall (t :: * -> *) b a.
Foldable t =>
(b -> a -> b) -> b -> t a -> b
foldl' Type -> Type -> Type
AppTy ((Type -> [Type] -> Type
mkAppTys Type
fun_ty [Type]
casted_arg_tys) Type -> KindCoercion -> Type
`mkCastTy` KindCoercion
res_co) [Type]
leftovers
  where
    ([KindCoercion]
arg_cos, KindCoercion
res_co) = HasDebugCallStack =>
KindCoercion
-> Pair Type -> [Type] -> ([KindCoercion], KindCoercion)
KindCoercion
-> Pair Type -> [Type] -> ([KindCoercion], KindCoercion)
decomposePiCos KindCoercion
co (KindCoercion -> Pair Type
coercionKind KindCoercion
co) [Type]
arg_tys
    ([Type]
args_to_cast, [Type]
leftovers) = [KindCoercion] -> [Type] -> ([Type], [Type])
forall b a. [b] -> [a] -> ([a], [a])
splitAtList [KindCoercion]
arg_cos [Type]
arg_tys
    casted_arg_tys :: [Type]
casted_arg_tys = (Type -> KindCoercion -> Type)
-> [Type] -> [KindCoercion] -> [Type]
forall a b c. (a -> b -> c) -> [a] -> [b] -> [c]
zipWith Type -> KindCoercion -> Type
mkCastTy [Type]
args_to_cast [KindCoercion]
arg_cos
mkAppTys (TyConApp TyCon
tc [Type]
tys1) [Type]
tys2 = TyCon -> [Type] -> Type
mkTyConApp TyCon
tc ([Type]
tys1 [Type] -> [Type] -> [Type]
forall a. [a] -> [a] -> [a]
++ [Type]
tys2)
mkAppTys Type
ty1                [Type]
tys2 = (Type -> Type -> Type) -> Type -> [Type] -> Type
forall (t :: * -> *) b a.
Foldable t =>
(b -> a -> b) -> b -> t a -> b
foldl' Type -> Type -> Type
AppTy Type
ty1 [Type]
tys2

-------------
splitAppTy_maybe :: Type -> Maybe (Type, Type)
-- ^ Attempt to take a type application apart, whether it is a
-- function, type constructor, or plain type application. Note
-- that type family applications are NEVER unsaturated by this!
splitAppTy_maybe :: Type -> Maybe (Type, Type)
splitAppTy_maybe Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty
                    = Type -> Maybe (Type, Type)
splitAppTy_maybe Type
ty'
splitAppTy_maybe Type
ty = HasDebugCallStack => Type -> Maybe (Type, Type)
Type -> Maybe (Type, Type)
repSplitAppTy_maybe Type
ty

-------------
repSplitAppTy_maybe :: HasDebugCallStack => Type -> Maybe (Type,Type)
-- ^ Does the AppTy split as in 'splitAppTy_maybe', but assumes that
-- any Core view stuff is already done
repSplitAppTy_maybe :: Type -> Maybe (Type, Type)
repSplitAppTy_maybe (FunTy AnonArgFlag
_ Type
ty1 Type
ty2)
  = (Type, Type) -> Maybe (Type, Type)
forall a. a -> Maybe a
Just (TyCon -> [Type] -> Type
TyConApp TyCon
funTyCon [Type
rep1, Type
rep2, Type
ty1], Type
ty2)
  where
    rep1 :: Type
rep1 = HasDebugCallStack => Type -> Type
Type -> Type
getRuntimeRep Type
ty1
    rep2 :: Type
rep2 = HasDebugCallStack => Type -> Type
Type -> Type
getRuntimeRep Type
ty2

repSplitAppTy_maybe (AppTy Type
ty1 Type
ty2)
  = (Type, Type) -> Maybe (Type, Type)
forall a. a -> Maybe a
Just (Type
ty1, Type
ty2)

repSplitAppTy_maybe (TyConApp TyCon
tc [Type]
tys)
  | Bool -> Bool
not (TyCon -> Bool
mustBeSaturated TyCon
tc) Bool -> Bool -> Bool
|| [Type]
tys [Type] -> Int -> Bool
forall a. [a] -> Int -> Bool
`lengthExceeds` TyCon -> Int
tyConArity TyCon
tc
  , Just ([Type]
tys', Type
ty') <- [Type] -> Maybe ([Type], Type)
forall a. [a] -> Maybe ([a], a)
snocView [Type]
tys
  = (Type, Type) -> Maybe (Type, Type)
forall a. a -> Maybe a
Just (TyCon -> [Type] -> Type
TyConApp TyCon
tc [Type]
tys', Type
ty')    -- Never create unsaturated type family apps!

repSplitAppTy_maybe Type
_other = Maybe (Type, Type)
forall a. Maybe a
Nothing

-- This one doesn't break apart (c => t).
-- See Note [Decomposing fat arrow c=>t]
-- Defined here to avoid module loops between Unify and TcType.
tcRepSplitAppTy_maybe :: Type -> Maybe (Type,Type)
-- ^ Does the AppTy split as in 'tcSplitAppTy_maybe', but assumes that
-- any coreView stuff is already done. Refuses to look through (c => t)
tcRepSplitAppTy_maybe :: Type -> Maybe (Type, Type)
tcRepSplitAppTy_maybe (FunTy { ft_af :: Type -> AnonArgFlag
ft_af = AnonArgFlag
af, ft_arg :: Type -> Type
ft_arg = Type
ty1, ft_res :: Type -> Type
ft_res = Type
ty2 })
  | AnonArgFlag
InvisArg <- AnonArgFlag
af
  = Maybe (Type, Type)
forall a. Maybe a
Nothing  -- See Note [Decomposing fat arrow c=>t]

  | Bool
otherwise
  = (Type, Type) -> Maybe (Type, Type)
forall a. a -> Maybe a
Just (TyCon -> [Type] -> Type
TyConApp TyCon
funTyCon [Type
rep1, Type
rep2, Type
ty1], Type
ty2)
  where
    rep1 :: Type
rep1 = HasDebugCallStack => Type -> Type
Type -> Type
getRuntimeRep Type
ty1
    rep2 :: Type
rep2 = HasDebugCallStack => Type -> Type
Type -> Type
getRuntimeRep Type
ty2

tcRepSplitAppTy_maybe (AppTy Type
ty1 Type
ty2)    = (Type, Type) -> Maybe (Type, Type)
forall a. a -> Maybe a
Just (Type
ty1, Type
ty2)
tcRepSplitAppTy_maybe (TyConApp TyCon
tc [Type]
tys)
  | Bool -> Bool
not (TyCon -> Bool
mustBeSaturated TyCon
tc) Bool -> Bool -> Bool
|| [Type]
tys [Type] -> Int -> Bool
forall a. [a] -> Int -> Bool
`lengthExceeds` TyCon -> Int
tyConArity TyCon
tc
  , Just ([Type]
tys', Type
ty') <- [Type] -> Maybe ([Type], Type)
forall a. [a] -> Maybe ([a], a)
snocView [Type]
tys
  = (Type, Type) -> Maybe (Type, Type)
forall a. a -> Maybe a
Just (TyCon -> [Type] -> Type
TyConApp TyCon
tc [Type]
tys', Type
ty')    -- Never create unsaturated type family apps!
tcRepSplitAppTy_maybe Type
_other = Maybe (Type, Type)
forall a. Maybe a
Nothing

-------------
splitAppTy :: Type -> (Type, Type)
-- ^ Attempts to take a type application apart, as in 'splitAppTy_maybe',
-- and panics if this is not possible
splitAppTy :: Type -> (Type, Type)
splitAppTy Type
ty = case Type -> Maybe (Type, Type)
splitAppTy_maybe Type
ty of
                Just (Type, Type)
pr -> (Type, Type)
pr
                Maybe (Type, Type)
Nothing -> String -> (Type, Type)
forall a. String -> a
panic String
"splitAppTy"

-------------
splitAppTys :: Type -> (Type, [Type])
-- ^ Recursively splits a type as far as is possible, leaving a residual
-- type being applied to and the type arguments applied to it. Never fails,
-- even if that means returning an empty list of type applications.
splitAppTys :: Type -> (Type, [Type])
splitAppTys Type
ty = Type -> Type -> [Type] -> (Type, [Type])
split Type
ty Type
ty []
  where
    split :: Type -> Type -> [Type] -> (Type, [Type])
split Type
orig_ty Type
ty [Type]
args | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Type -> [Type] -> (Type, [Type])
split Type
orig_ty Type
ty' [Type]
args
    split Type
_       (AppTy Type
ty Type
arg)        [Type]
args = Type -> Type -> [Type] -> (Type, [Type])
split Type
ty Type
ty (Type
argType -> [Type] -> [Type]
forall a. a -> [a] -> [a]
:[Type]
args)
    split Type
_       (TyConApp TyCon
tc [Type]
tc_args) [Type]
args
      = let -- keep type families saturated
            n :: Int
n | TyCon -> Bool
mustBeSaturated TyCon
tc = TyCon -> Int
tyConArity TyCon
tc
              | Bool
otherwise          = Int
0
            ([Type]
tc_args1, [Type]
tc_args2) = Int -> [Type] -> ([Type], [Type])
forall a. Int -> [a] -> ([a], [a])
splitAt Int
n [Type]
tc_args
        in
        (TyCon -> [Type] -> Type
TyConApp TyCon
tc [Type]
tc_args1, [Type]
tc_args2 [Type] -> [Type] -> [Type]
forall a. [a] -> [a] -> [a]
++ [Type]
args)
    split Type
_   (FunTy AnonArgFlag
_ Type
ty1 Type
ty2) [Type]
args
      = ASSERT( null args )
        (TyCon -> [Type] -> Type
TyConApp TyCon
funTyCon [], [Type
rep1, Type
rep2, Type
ty1, Type
ty2])
      where
        rep1 :: Type
rep1 = HasDebugCallStack => Type -> Type
Type -> Type
getRuntimeRep Type
ty1
        rep2 :: Type
rep2 = HasDebugCallStack => Type -> Type
Type -> Type
getRuntimeRep Type
ty2

    split Type
orig_ty Type
_                     [Type]
args  = (Type
orig_ty, [Type]
args)

-- | Like 'splitAppTys', but doesn't look through type synonyms
repSplitAppTys :: HasDebugCallStack => Type -> (Type, [Type])
repSplitAppTys :: Type -> (Type, [Type])
repSplitAppTys Type
ty = Type -> [Type] -> (Type, [Type])
split Type
ty []
  where
    split :: Type -> [Type] -> (Type, [Type])
split (AppTy Type
ty Type
arg) [Type]
args = Type -> [Type] -> (Type, [Type])
split Type
ty (Type
argType -> [Type] -> [Type]
forall a. a -> [a] -> [a]
:[Type]
args)
    split (TyConApp TyCon
tc [Type]
tc_args) [Type]
args
      = let n :: Int
n | TyCon -> Bool
mustBeSaturated TyCon
tc = TyCon -> Int
tyConArity TyCon
tc
              | Bool
otherwise          = Int
0
            ([Type]
tc_args1, [Type]
tc_args2) = Int -> [Type] -> ([Type], [Type])
forall a. Int -> [a] -> ([a], [a])
splitAt Int
n [Type]
tc_args
        in
        (TyCon -> [Type] -> Type
TyConApp TyCon
tc [Type]
tc_args1, [Type]
tc_args2 [Type] -> [Type] -> [Type]
forall a. [a] -> [a] -> [a]
++ [Type]
args)
    split (FunTy AnonArgFlag
_ Type
ty1 Type
ty2) [Type]
args
      = ASSERT( null args )
        (TyCon -> [Type] -> Type
TyConApp TyCon
funTyCon [], [Type
rep1, Type
rep2, Type
ty1, Type
ty2])
      where
        rep1 :: Type
rep1 = HasDebugCallStack => Type -> Type
Type -> Type
getRuntimeRep Type
ty1
        rep2 :: Type
rep2 = HasDebugCallStack => Type -> Type
Type -> Type
getRuntimeRep Type
ty2

    split Type
ty [Type]
args = (Type
ty, [Type]
args)

{-
                      LitTy
                      ~~~~~
-}

mkNumLitTy :: Integer -> Type
mkNumLitTy :: Integer -> Type
mkNumLitTy Integer
n = TyLit -> Type
LitTy (Integer -> TyLit
NumTyLit Integer
n)

-- | Is this a numeric literal. We also look through type synonyms.
isNumLitTy :: Type -> Maybe Integer
isNumLitTy :: Type -> Maybe Integer
isNumLitTy Type
ty | Just Type
ty1 <- Type -> Maybe Type
coreView Type
ty = Type -> Maybe Integer
isNumLitTy Type
ty1
isNumLitTy (LitTy (NumTyLit Integer
n)) = Integer -> Maybe Integer
forall a. a -> Maybe a
Just Integer
n
isNumLitTy Type
_                    = Maybe Integer
forall a. Maybe a
Nothing

mkStrLitTy :: FastString -> Type
mkStrLitTy :: FastString -> Type
mkStrLitTy FastString
s = TyLit -> Type
LitTy (FastString -> TyLit
StrTyLit FastString
s)

-- | Is this a symbol literal. We also look through type synonyms.
isStrLitTy :: Type -> Maybe FastString
isStrLitTy :: Type -> Maybe FastString
isStrLitTy Type
ty | Just Type
ty1 <- Type -> Maybe Type
coreView Type
ty = Type -> Maybe FastString
isStrLitTy Type
ty1
isStrLitTy (LitTy (StrTyLit FastString
s)) = FastString -> Maybe FastString
forall a. a -> Maybe a
Just FastString
s
isStrLitTy Type
_                    = Maybe FastString
forall a. Maybe a
Nothing

-- | Is this a type literal (symbol or numeric).
isLitTy :: Type -> Maybe TyLit
isLitTy :: Type -> Maybe TyLit
isLitTy Type
ty | Just Type
ty1 <- Type -> Maybe Type
coreView Type
ty = Type -> Maybe TyLit
isLitTy Type
ty1
isLitTy (LitTy TyLit
l)                    = TyLit -> Maybe TyLit
forall a. a -> Maybe a
Just TyLit
l
isLitTy Type
_                            = Maybe TyLit
forall a. Maybe a
Nothing

-- | Is this type a custom user error?
-- If so, give us the kind and the error message.
userTypeError_maybe :: Type -> Maybe Type
userTypeError_maybe :: Type -> Maybe Type
userTypeError_maybe Type
t
  = do { (TyCon
tc, Type
_kind : Type
msg : [Type]
_) <- HasDebugCallStack => Type -> Maybe (TyCon, [Type])
Type -> Maybe (TyCon, [Type])
splitTyConApp_maybe Type
t
          -- There may be more than 2 arguments, if the type error is
          -- used as a type constructor (e.g. at kind `Type -> Type`).

       ; Bool -> Maybe ()
forall (f :: * -> *). Alternative f => Bool -> f ()
guard (TyCon -> Name
tyConName TyCon
tc Name -> Name -> Bool
forall a. Eq a => a -> a -> Bool
== Name
errorMessageTypeErrorFamName)
       ; Type -> Maybe Type
forall (m :: * -> *) a. Monad m => a -> m a
return Type
msg }

-- | Render a type corresponding to a user type error into a SDoc.
pprUserTypeErrorTy :: Type -> SDoc
pprUserTypeErrorTy :: Type -> SDoc
pprUserTypeErrorTy Type
ty =
  case HasDebugCallStack => Type -> Maybe (TyCon, [Type])
Type -> Maybe (TyCon, [Type])
splitTyConApp_maybe Type
ty of

    -- Text "Something"
    Just (TyCon
tc,[Type
txt])
      | TyCon -> Name
tyConName TyCon
tc Name -> Name -> Bool
forall a. Eq a => a -> a -> Bool
== Name
typeErrorTextDataConName
      , Just FastString
str <- Type -> Maybe FastString
isStrLitTy Type
txt -> FastString -> SDoc
ftext FastString
str

    -- ShowType t
    Just (TyCon
tc,[Type
_k,Type
t])
      | TyCon -> Name
tyConName TyCon
tc Name -> Name -> Bool
forall a. Eq a => a -> a -> Bool
== Name
typeErrorShowTypeDataConName -> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
t

    -- t1 :<>: t2
    Just (TyCon
tc,[Type
t1,Type
t2])
      | TyCon -> Name
tyConName TyCon
tc Name -> Name -> Bool
forall a. Eq a => a -> a -> Bool
== Name
typeErrorAppendDataConName ->
        Type -> SDoc
pprUserTypeErrorTy Type
t1 SDoc -> SDoc -> SDoc
<> Type -> SDoc
pprUserTypeErrorTy Type
t2

    -- t1 :$$: t2
    Just (TyCon
tc,[Type
t1,Type
t2])
      | TyCon -> Name
tyConName TyCon
tc Name -> Name -> Bool
forall a. Eq a => a -> a -> Bool
== Name
typeErrorVAppendDataConName ->
        Type -> SDoc
pprUserTypeErrorTy Type
t1 SDoc -> SDoc -> SDoc
$$ Type -> SDoc
pprUserTypeErrorTy Type
t2

    -- An unevaluated type function
    Maybe (TyCon, [Type])
_ -> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
ty




{-
---------------------------------------------------------------------
                                FunTy
                                ~~~~~

Note [Representation of function types]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Functions (e.g. Int -> Char) can be thought of as being applications
of funTyCon (known in Haskell surface syntax as (->)),

    (->) :: forall (r1 :: RuntimeRep) (r2 :: RuntimeRep)
                   (a :: TYPE r1) (b :: TYPE r2).
            a -> b -> Type

However, for efficiency's sake we represent saturated applications of (->)
with FunTy. For instance, the type,

    (->) r1 r2 a b

is equivalent to,

    FunTy (Anon a) b

Note how the RuntimeReps are implied in the FunTy representation. For this
reason we must be careful when recontructing the TyConApp representation (see,
for instance, splitTyConApp_maybe).

In the compiler we maintain the invariant that all saturated applications of
(->) are represented with FunTy.

See #11714.
-}

splitFunTy :: Type -> (Type, Type)
-- ^ Attempts to extract the argument and result types from a type, and
-- panics if that is not possible. See also 'splitFunTy_maybe'
splitFunTy :: Type -> (Type, Type)
splitFunTy Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> (Type, Type)
splitFunTy Type
ty'
splitFunTy (FunTy AnonArgFlag
_ Type
arg Type
res) = (Type
arg, Type
res)
splitFunTy Type
other             = String -> SDoc -> (Type, Type)
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"splitFunTy" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
other)

splitFunTy_maybe :: Type -> Maybe (Type, Type)
-- ^ Attempts to extract the argument and result types from a type
splitFunTy_maybe :: Type -> Maybe (Type, Type)
splitFunTy_maybe Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Maybe (Type, Type)
splitFunTy_maybe Type
ty'
splitFunTy_maybe (FunTy AnonArgFlag
_ Type
arg Type
res) = (Type, Type) -> Maybe (Type, Type)
forall a. a -> Maybe a
Just (Type
arg, Type
res)
splitFunTy_maybe Type
_                 = Maybe (Type, Type)
forall a. Maybe a
Nothing

splitFunTys :: Type -> ([Type], Type)
splitFunTys :: Type -> ([Type], Type)
splitFunTys Type
ty = [Type] -> Type -> Type -> ([Type], Type)
split [] Type
ty Type
ty
  where
    split :: [Type] -> Type -> Type -> ([Type], Type)
split [Type]
args Type
orig_ty Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = [Type] -> Type -> Type -> ([Type], Type)
split [Type]
args Type
orig_ty Type
ty'
    split [Type]
args Type
_       (FunTy AnonArgFlag
_ Type
arg Type
res) = [Type] -> Type -> Type -> ([Type], Type)
split (Type
argType -> [Type] -> [Type]
forall a. a -> [a] -> [a]
:[Type]
args) Type
res Type
res
    split [Type]
args Type
orig_ty Type
_                 = ([Type] -> [Type]
forall a. [a] -> [a]
reverse [Type]
args, Type
orig_ty)

funResultTy :: Type -> Type
-- ^ Extract the function result type and panic if that is not possible
funResultTy :: Type -> Type
funResultTy Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Type
funResultTy Type
ty'
funResultTy (FunTy { ft_res :: Type -> Type
ft_res = Type
res }) = Type
res
funResultTy Type
ty                       = String -> SDoc -> Type
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"funResultTy" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
ty)

funArgTy :: Type -> Type
-- ^ Extract the function argument type and panic if that is not possible
funArgTy :: Type -> Type
funArgTy Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Type
funArgTy Type
ty'
funArgTy (FunTy { ft_arg :: Type -> Type
ft_arg = Type
arg })    = Type
arg
funArgTy Type
ty                           = String -> SDoc -> Type
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"funArgTy" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
ty)

-- ^ Just like 'piResultTys' but for a single argument
-- Try not to iterate 'piResultTy', because it's inefficient to substitute
-- one variable at a time; instead use 'piResultTys"
piResultTy :: HasDebugCallStack => Type -> Type ->  Type
piResultTy :: Type -> Type -> Type
piResultTy Type
ty Type
arg = case Type -> Type -> Maybe Type
piResultTy_maybe Type
ty Type
arg of
                      Just Type
res -> Type
res
                      Maybe Type
Nothing  -> String -> SDoc -> Type
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"piResultTy" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
ty SDoc -> SDoc -> SDoc
$$ Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
arg)

piResultTy_maybe :: Type -> Type -> Maybe Type
-- We don't need a 'tc' version, because
-- this function behaves the same for Type and Constraint
piResultTy_maybe :: Type -> Type -> Maybe Type
piResultTy_maybe Type
ty Type
arg
  | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Type -> Maybe Type
piResultTy_maybe Type
ty' Type
arg

  | FunTy { ft_res :: Type -> Type
ft_res = Type
res } <- Type
ty
  = Type -> Maybe Type
forall a. a -> Maybe a
Just Type
res

  | ForAllTy (Bndr TyVar
tv ArgFlag
_) Type
res <- Type
ty
  = let empty_subst :: TCvSubst
empty_subst = InScopeSet -> TCvSubst
mkEmptyTCvSubst (InScopeSet -> TCvSubst) -> InScopeSet -> TCvSubst
forall a b. (a -> b) -> a -> b
$ VarSet -> InScopeSet
mkInScopeSet (VarSet -> InScopeSet) -> VarSet -> InScopeSet
forall a b. (a -> b) -> a -> b
$
                      [Type] -> VarSet
tyCoVarsOfTypes [Type
arg,Type
res]
    in Type -> Maybe Type
forall a. a -> Maybe a
Just (HasCallStack => TCvSubst -> Type -> Type
TCvSubst -> Type -> Type
substTy (TCvSubst -> TyVar -> Type -> TCvSubst
extendTCvSubst TCvSubst
empty_subst TyVar
tv Type
arg) Type
res)

  | Bool
otherwise
  = Maybe Type
forall a. Maybe a
Nothing

-- | (piResultTys f_ty [ty1, .., tyn]) gives the type of (f ty1 .. tyn)
--   where f :: f_ty
-- 'piResultTys' is interesting because:
--      1. 'f_ty' may have more for-alls than there are args
--      2. Less obviously, it may have fewer for-alls
-- For case 2. think of:
--   piResultTys (forall a.a) [forall b.b, Int]
-- This really can happen, but only (I think) in situations involving
-- undefined.  For example:
--       undefined :: forall a. a
-- Term: undefined @(forall b. b->b) @Int
-- This term should have type (Int -> Int), but notice that
-- there are more type args than foralls in 'undefined's type.

-- If you edit this function, you may need to update the GHC formalism
-- See Note [GHC Formalism] in coreSyn/CoreLint.hs

-- This is a heavily used function (e.g. from typeKind),
-- so we pay attention to efficiency, especially in the special case
-- where there are no for-alls so we are just dropping arrows from
-- a function type/kind.
piResultTys :: HasDebugCallStack => Type -> [Type] -> Type
piResultTys :: Type -> [Type] -> Type
piResultTys Type
ty [] = Type
ty
piResultTys Type
ty orig_args :: [Type]
orig_args@(Type
arg:[Type]
args)
  | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty
  = HasDebugCallStack => Type -> [Type] -> Type
Type -> [Type] -> Type
piResultTys Type
ty' [Type]
orig_args

  | FunTy { ft_res :: Type -> Type
ft_res = Type
res } <- Type
ty
  = HasDebugCallStack => Type -> [Type] -> Type
Type -> [Type] -> Type
piResultTys Type
res [Type]
args

  | ForAllTy (Bndr TyVar
tv ArgFlag
_) Type
res <- Type
ty
  = TCvSubst -> Type -> [Type] -> Type
go (TCvSubst -> TyVar -> Type -> TCvSubst
extendTCvSubst TCvSubst
init_subst TyVar
tv Type
arg) Type
res [Type]
args

  | Bool
otherwise
  = String -> SDoc -> Type
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"piResultTys1" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
ty SDoc -> SDoc -> SDoc
$$ [Type] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Type]
orig_args)
  where
    init_subst :: TCvSubst
init_subst = InScopeSet -> TCvSubst
mkEmptyTCvSubst (InScopeSet -> TCvSubst) -> InScopeSet -> TCvSubst
forall a b. (a -> b) -> a -> b
$ VarSet -> InScopeSet
mkInScopeSet ([Type] -> VarSet
tyCoVarsOfTypes (Type
tyType -> [Type] -> [Type]
forall a. a -> [a] -> [a]
:[Type]
orig_args))

    go :: TCvSubst -> Type -> [Type] -> Type
    go :: TCvSubst -> Type -> [Type] -> Type
go TCvSubst
subst Type
ty [] = TCvSubst -> Type -> Type
substTyUnchecked TCvSubst
subst Type
ty

    go TCvSubst
subst Type
ty all_args :: [Type]
all_args@(Type
arg:[Type]
args)
      | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty
      = TCvSubst -> Type -> [Type] -> Type
go TCvSubst
subst Type
ty' [Type]
all_args

      | FunTy { ft_res :: Type -> Type
ft_res = Type
res } <- Type
ty
      = TCvSubst -> Type -> [Type] -> Type
go TCvSubst
subst Type
res [Type]
args

      | ForAllTy (Bndr TyVar
tv ArgFlag
_) Type
res <- Type
ty
      = TCvSubst -> Type -> [Type] -> Type
go (TCvSubst -> TyVar -> Type -> TCvSubst
extendTCvSubst TCvSubst
subst TyVar
tv Type
arg) Type
res [Type]
args

      | Bool -> Bool
not (TCvSubst -> Bool
isEmptyTCvSubst TCvSubst
subst)  -- See Note [Care with kind instantiation]
      = TCvSubst -> Type -> [Type] -> Type
go TCvSubst
init_subst
          (HasCallStack => TCvSubst -> Type -> Type
TCvSubst -> Type -> Type
substTy TCvSubst
subst Type
ty)
          [Type]
all_args

      | Bool
otherwise
      = -- We have not run out of arguments, but the function doesn't
        -- have the right kind to apply to them; so panic.
        -- Without the explicit isEmptyVarEnv test, an ill-kinded type
        -- would give an infniite loop, which is very unhelpful
        -- c.f. #15473
        String -> SDoc -> Type
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"piResultTys2" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
ty SDoc -> SDoc -> SDoc
$$ [Type] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Type]
orig_args SDoc -> SDoc -> SDoc
$$ [Type] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Type]
all_args)

applyTysX :: [TyVar] -> Type -> [Type] -> Type
-- applyTyxX beta-reduces (/\tvs. body_ty) arg_tys
-- Assumes that (/\tvs. body_ty) is closed
applyTysX :: [TyVar] -> Type -> [Type] -> Type
applyTysX [TyVar]
tvs Type
body_ty [Type]
arg_tys
  = ASSERT2( arg_tys `lengthAtLeast` n_tvs, pp_stuff )
    ASSERT2( tyCoVarsOfType body_ty `subVarSet` mkVarSet tvs, pp_stuff )
    Type -> [Type] -> Type
mkAppTys (HasCallStack => [TyVar] -> [Type] -> Type -> Type
[TyVar] -> [Type] -> Type -> Type
substTyWith [TyVar]
tvs (Int -> [Type] -> [Type]
forall a. Int -> [a] -> [a]
take Int
n_tvs [Type]
arg_tys) Type
body_ty)
             (Int -> [Type] -> [Type]
forall a. Int -> [a] -> [a]
drop Int
n_tvs [Type]
arg_tys)
  where
    pp_stuff :: SDoc
pp_stuff = [SDoc] -> SDoc
vcat [[TyVar] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyVar]
tvs, Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
body_ty, [Type] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Type]
arg_tys]
    n_tvs :: Int
n_tvs = [TyVar] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [TyVar]
tvs



{- Note [Care with kind instantiation]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Suppose we have
  T :: forall k. k
and we are finding the kind of
  T (forall b. b -> b) * Int
Then
  T (forall b. b->b) :: k[ k :-> forall b. b->b]
                     :: forall b. b -> b
So
  T (forall b. b->b) * :: (b -> b)[ b :-> *]
                       :: * -> *

In other words we must intantiate the forall!

Similarly (#15428)
   S :: forall k f. k -> f k
and we are finding the kind of
   S * (* ->) Int Bool
We have
   S * (* ->) :: (k -> f k)[ k :-> *, f :-> (* ->)]
              :: * -> * -> *
So again we must instantiate.

The same thing happens in ToIface.toIfaceAppArgsX.


---------------------------------------------------------------------
                                TyConApp
                                ~~~~~~~~
-}

-- | A key function: builds a 'TyConApp' or 'FunTy' as appropriate to
-- its arguments.  Applies its arguments to the constructor from left to right.
mkTyConApp :: TyCon -> [Type] -> Type
mkTyConApp :: TyCon -> [Type] -> Type
mkTyConApp TyCon
tycon [Type]
tys
  | TyCon -> Bool
isFunTyCon TyCon
tycon
  , [Type
_rep1,Type
_rep2,Type
ty1,Type
ty2] <- [Type]
tys
  = FunTy :: AnonArgFlag -> Type -> Type -> Type
FunTy { ft_af :: AnonArgFlag
ft_af = AnonArgFlag
VisArg, ft_arg :: Type
ft_arg = Type
ty1, ft_res :: Type
ft_res = Type
ty2 }
    -- The FunTyCon (->) is always a visible one

  | Bool
otherwise
  = TyCon -> [Type] -> Type
TyConApp TyCon
tycon [Type]
tys

-- splitTyConApp "looks through" synonyms, because they don't
-- mean a distinct type, but all other type-constructor applications
-- including functions are returned as Just ..

-- | Retrieve the tycon heading this type, if there is one. Does /not/
-- look through synonyms.
tyConAppTyConPicky_maybe :: Type -> Maybe TyCon
tyConAppTyConPicky_maybe :: Type -> Maybe TyCon
tyConAppTyConPicky_maybe (TyConApp TyCon
tc [Type]
_) = TyCon -> Maybe TyCon
forall a. a -> Maybe a
Just TyCon
tc
tyConAppTyConPicky_maybe (FunTy {})      = TyCon -> Maybe TyCon
forall a. a -> Maybe a
Just TyCon
funTyCon
tyConAppTyConPicky_maybe Type
_               = Maybe TyCon
forall a. Maybe a
Nothing


-- | The same as @fst . splitTyConApp@
tyConAppTyCon_maybe :: Type -> Maybe TyCon
tyConAppTyCon_maybe :: Type -> Maybe TyCon
tyConAppTyCon_maybe Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Maybe TyCon
tyConAppTyCon_maybe Type
ty'
tyConAppTyCon_maybe (TyConApp TyCon
tc [Type]
_) = TyCon -> Maybe TyCon
forall a. a -> Maybe a
Just TyCon
tc
tyConAppTyCon_maybe (FunTy {})      = TyCon -> Maybe TyCon
forall a. a -> Maybe a
Just TyCon
funTyCon
tyConAppTyCon_maybe Type
_               = Maybe TyCon
forall a. Maybe a
Nothing

tyConAppTyCon :: Type -> TyCon
tyConAppTyCon :: Type -> TyCon
tyConAppTyCon Type
ty = Type -> Maybe TyCon
tyConAppTyCon_maybe Type
ty Maybe TyCon -> TyCon -> TyCon
forall a. Maybe a -> a -> a
`orElse` String -> SDoc -> TyCon
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"tyConAppTyCon" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
ty)

-- | The same as @snd . splitTyConApp@
tyConAppArgs_maybe :: Type -> Maybe [Type]
tyConAppArgs_maybe :: Type -> Maybe [Type]
tyConAppArgs_maybe Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Maybe [Type]
tyConAppArgs_maybe Type
ty'
tyConAppArgs_maybe (TyConApp TyCon
_ [Type]
tys) = [Type] -> Maybe [Type]
forall a. a -> Maybe a
Just [Type]
tys
tyConAppArgs_maybe (FunTy AnonArgFlag
_ Type
arg Type
res)
  | Just Type
rep1 <- HasDebugCallStack => Type -> Maybe Type
Type -> Maybe Type
getRuntimeRep_maybe Type
arg
  , Just Type
rep2 <- HasDebugCallStack => Type -> Maybe Type
Type -> Maybe Type
getRuntimeRep_maybe Type
res
  = [Type] -> Maybe [Type]
forall a. a -> Maybe a
Just [Type
rep1, Type
rep2, Type
arg, Type
res]
tyConAppArgs_maybe Type
_  = Maybe [Type]
forall a. Maybe a
Nothing

tyConAppArgs :: Type -> [Type]
tyConAppArgs :: Type -> [Type]
tyConAppArgs Type
ty = Type -> Maybe [Type]
tyConAppArgs_maybe Type
ty Maybe [Type] -> [Type] -> [Type]
forall a. Maybe a -> a -> a
`orElse` String -> SDoc -> [Type]
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"tyConAppArgs" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
ty)

tyConAppArgN :: Int -> Type -> Type
-- Executing Nth
tyConAppArgN :: Int -> Type -> Type
tyConAppArgN Int
n Type
ty
  = case Type -> Maybe [Type]
tyConAppArgs_maybe Type
ty of
      Just [Type]
tys -> ASSERT2( tys `lengthExceeds` n, ppr n <+> ppr tys ) tys `getNth` n
      Maybe [Type]
Nothing  -> String -> SDoc -> Type
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"tyConAppArgN" (Int -> SDoc
forall a. Outputable a => a -> SDoc
ppr Int
n SDoc -> SDoc -> SDoc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
ty)

-- | Attempts to tease a type apart into a type constructor and the application
-- of a number of arguments to that constructor. Panics if that is not possible.
-- See also 'splitTyConApp_maybe'
splitTyConApp :: Type -> (TyCon, [Type])
splitTyConApp :: Type -> (TyCon, [Type])
splitTyConApp Type
ty = case HasDebugCallStack => Type -> Maybe (TyCon, [Type])
Type -> Maybe (TyCon, [Type])
splitTyConApp_maybe Type
ty of
                   Just (TyCon, [Type])
stuff -> (TyCon, [Type])
stuff
                   Maybe (TyCon, [Type])
Nothing    -> String -> SDoc -> (TyCon, [Type])
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"splitTyConApp" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
ty)

-- | Attempts to tease a type apart into a type constructor and the application
-- of a number of arguments to that constructor
splitTyConApp_maybe :: HasDebugCallStack => Type -> Maybe (TyCon, [Type])
splitTyConApp_maybe :: Type -> Maybe (TyCon, [Type])
splitTyConApp_maybe Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = HasDebugCallStack => Type -> Maybe (TyCon, [Type])
Type -> Maybe (TyCon, [Type])
splitTyConApp_maybe Type
ty'
splitTyConApp_maybe Type
ty                           = HasDebugCallStack => Type -> Maybe (TyCon, [Type])
Type -> Maybe (TyCon, [Type])
repSplitTyConApp_maybe Type
ty

-- | Split a type constructor application into its type constructor and
-- applied types. Note that this may fail in the case of a 'FunTy' with an
-- argument of unknown kind 'FunTy' (e.g. @FunTy (a :: k) Int@. since the kind
-- of @a@ isn't of the form @TYPE rep@). Consequently, you may need to zonk your
-- type before using this function.
--
-- If you only need the 'TyCon', consider using 'tcTyConAppTyCon_maybe'.
tcSplitTyConApp_maybe :: HasCallStack => Type -> Maybe (TyCon, [Type])
-- Defined here to avoid module loops between Unify and TcType.
tcSplitTyConApp_maybe :: Type -> Maybe (TyCon, [Type])
tcSplitTyConApp_maybe Type
ty | Just Type
ty' <- Type -> Maybe Type
tcView Type
ty = HasCallStack => Type -> Maybe (TyCon, [Type])
Type -> Maybe (TyCon, [Type])
tcSplitTyConApp_maybe Type
ty'
tcSplitTyConApp_maybe Type
ty                         = HasDebugCallStack => Type -> Maybe (TyCon, [Type])
Type -> Maybe (TyCon, [Type])
repSplitTyConApp_maybe Type
ty

-------------------
repSplitTyConApp_maybe :: HasDebugCallStack => Type -> Maybe (TyCon, [Type])
-- ^ Like 'splitTyConApp_maybe', but doesn't look through synonyms. This
-- assumes the synonyms have already been dealt with.
--
-- Moreover, for a FunTy, it only succeeds if the argument types
-- have enough info to extract the runtime-rep arguments that
-- the funTyCon requires.  This will usually be true;
-- but may be temporarily false during canonicalization:
--     see Note [FunTy and decomposing tycon applications] in TcCanonical
--
repSplitTyConApp_maybe :: Type -> Maybe (TyCon, [Type])
repSplitTyConApp_maybe (TyConApp TyCon
tc [Type]
tys) = (TyCon, [Type]) -> Maybe (TyCon, [Type])
forall a. a -> Maybe a
Just (TyCon
tc, [Type]
tys)
repSplitTyConApp_maybe (FunTy AnonArgFlag
_ Type
arg Type
res)
  | Just Type
arg_rep <- HasDebugCallStack => Type -> Maybe Type
Type -> Maybe Type
getRuntimeRep_maybe Type
arg
  , Just Type
res_rep <- HasDebugCallStack => Type -> Maybe Type
Type -> Maybe Type
getRuntimeRep_maybe Type
res
  = (TyCon, [Type]) -> Maybe (TyCon, [Type])
forall a. a -> Maybe a
Just (TyCon
funTyCon, [Type
arg_rep, Type
res_rep, Type
arg, Type
res])
repSplitTyConApp_maybe Type
_ = Maybe (TyCon, [Type])
forall a. Maybe a
Nothing

-------------------
-- | Attempts to tease a list type apart and gives the type of the elements if
-- successful (looks through type synonyms)
splitListTyConApp_maybe :: Type -> Maybe Type
splitListTyConApp_maybe :: Type -> Maybe Type
splitListTyConApp_maybe Type
ty = case HasDebugCallStack => Type -> Maybe (TyCon, [Type])
Type -> Maybe (TyCon, [Type])
splitTyConApp_maybe Type
ty of
  Just (TyCon
tc,[Type
e]) | TyCon
tc TyCon -> TyCon -> Bool
forall a. Eq a => a -> a -> Bool
== TyCon
listTyCon -> Type -> Maybe Type
forall a. a -> Maybe a
Just Type
e
  Maybe (TyCon, [Type])
_other                          -> Maybe Type
forall a. Maybe a
Nothing

nextRole :: Type -> Role
nextRole :: Type -> Role
nextRole Type
ty
  | Just (TyCon
tc, [Type]
tys) <- HasDebugCallStack => Type -> Maybe (TyCon, [Type])
Type -> Maybe (TyCon, [Type])
splitTyConApp_maybe Type
ty
  , let num_tys :: Int
num_tys = [Type] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [Type]
tys
  , Int
num_tys Int -> Int -> Bool
forall a. Ord a => a -> a -> Bool
< TyCon -> Int
tyConArity TyCon
tc
  = TyCon -> [Role]
tyConRoles TyCon
tc [Role] -> Int -> Role
forall a. Outputable a => [a] -> Int -> a
`getNth` Int
num_tys

  | Bool
otherwise
  = Role
Nominal

newTyConInstRhs :: TyCon -> [Type] -> Type
-- ^ Unwrap one 'layer' of newtype on a type constructor and its
-- arguments, using an eta-reduced version of the @newtype@ if possible.
-- This requires tys to have at least @newTyConInstArity tycon@ elements.
newTyConInstRhs :: TyCon -> [Type] -> Type
newTyConInstRhs TyCon
tycon [Type]
tys
    = ASSERT2( tvs `leLength` tys, ppr tycon $$ ppr tys $$ ppr tvs )
      [TyVar] -> Type -> [Type] -> Type
applyTysX [TyVar]
tvs Type
rhs [Type]
tys
  where
    ([TyVar]
tvs, Type
rhs) = TyCon -> ([TyVar], Type)
newTyConEtadRhs TyCon
tycon

{-
---------------------------------------------------------------------
                           CastTy
                           ~~~~~~
A casted type has its *kind* casted into something new.
-}

splitCastTy_maybe :: Type -> Maybe (Type, Coercion)
splitCastTy_maybe :: Type -> Maybe (Type, KindCoercion)
splitCastTy_maybe Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Maybe (Type, KindCoercion)
splitCastTy_maybe Type
ty'
splitCastTy_maybe (CastTy Type
ty KindCoercion
co)               = (Type, KindCoercion) -> Maybe (Type, KindCoercion)
forall a. a -> Maybe a
Just (Type
ty, KindCoercion
co)
splitCastTy_maybe Type
_                            = Maybe (Type, KindCoercion)
forall a. Maybe a
Nothing

-- | Make a 'CastTy'. The Coercion must be nominal. Checks the
-- Coercion for reflexivity, dropping it if it's reflexive.
-- See Note [Respecting definitional equality] in TyCoRep
mkCastTy :: Type -> Coercion -> Type
mkCastTy :: Type -> KindCoercion -> Type
mkCastTy Type
ty KindCoercion
co | KindCoercion -> Bool
isReflexiveCo KindCoercion
co = Type
ty  -- (EQ2) from the Note
-- NB: Do the slow check here. This is important to keep the splitXXX
-- functions working properly. Otherwise, we may end up with something
-- like (((->) |> something_reflexive_but_not_obviously_so) biz baz)
-- fails under splitFunTy_maybe. This happened with the cheaper check
-- in test dependent/should_compile/dynamic-paper.

mkCastTy (CastTy Type
ty KindCoercion
co1) KindCoercion
co2
  -- (EQ3) from the Note
  = Type -> KindCoercion -> Type
mkCastTy Type
ty (KindCoercion
co1 KindCoercion -> KindCoercion -> KindCoercion
`mkTransCo` KindCoercion
co2)
      -- call mkCastTy again for the reflexivity check

mkCastTy (ForAllTy (Bndr TyVar
tv ArgFlag
vis) Type
inner_ty) KindCoercion
co
  -- (EQ4) from the Note
  | TyVar -> Bool
isTyVar TyVar
tv
  , let fvs :: VarSet
fvs = KindCoercion -> VarSet
tyCoVarsOfCo KindCoercion
co
  = -- have to make sure that pushing the co in doesn't capture the bound var!
    if TyVar
tv TyVar -> VarSet -> Bool
`elemVarSet` VarSet
fvs
    then let empty_subst :: TCvSubst
empty_subst = InScopeSet -> TCvSubst
mkEmptyTCvSubst (VarSet -> InScopeSet
mkInScopeSet VarSet
fvs)
             (TCvSubst
subst, TyVar
tv') = HasCallStack => TCvSubst -> TyVar -> (TCvSubst, TyVar)
TCvSubst -> TyVar -> (TCvSubst, TyVar)
substVarBndr TCvSubst
empty_subst TyVar
tv
         in VarBndr TyVar ArgFlag -> Type -> Type
ForAllTy (TyVar -> ArgFlag -> VarBndr TyVar ArgFlag
forall var argf. var -> argf -> VarBndr var argf
Bndr TyVar
tv' ArgFlag
vis) (HasCallStack => TCvSubst -> Type -> Type
TCvSubst -> Type -> Type
substTy TCvSubst
subst Type
inner_ty Type -> KindCoercion -> Type
`mkCastTy` KindCoercion
co)
    else VarBndr TyVar ArgFlag -> Type -> Type
ForAllTy (TyVar -> ArgFlag -> VarBndr TyVar ArgFlag
forall var argf. var -> argf -> VarBndr var argf
Bndr TyVar
tv ArgFlag
vis) (Type
inner_ty Type -> KindCoercion -> Type
`mkCastTy` KindCoercion
co)

mkCastTy Type
ty KindCoercion
co = Type -> KindCoercion -> Type
CastTy Type
ty KindCoercion
co

tyConBindersTyCoBinders :: [TyConBinder] -> [TyCoBinder]
-- Return the tyConBinders in TyCoBinder form
tyConBindersTyCoBinders :: [TyConBinder] -> [TyCoBinder]
tyConBindersTyCoBinders = (TyConBinder -> TyCoBinder) -> [TyConBinder] -> [TyCoBinder]
forall a b. (a -> b) -> [a] -> [b]
map TyConBinder -> TyCoBinder
to_tyb
  where
    to_tyb :: TyConBinder -> TyCoBinder
to_tyb (Bndr TyVar
tv (NamedTCB ArgFlag
vis)) = VarBndr TyVar ArgFlag -> TyCoBinder
Named (TyVar -> ArgFlag -> VarBndr TyVar ArgFlag
forall var argf. var -> argf -> VarBndr var argf
Bndr TyVar
tv ArgFlag
vis)
    to_tyb (Bndr TyVar
tv (AnonTCB AnonArgFlag
af))   = AnonArgFlag -> Type -> TyCoBinder
Anon AnonArgFlag
af (TyVar -> Type
varType TyVar
tv)

-- | Drop the cast on a type, if any. If there is no
-- cast, just return the original type. This is rarely what
-- you want. The CastTy data constructor (in TyCoRep) has the
-- invariant that another CastTy is not inside. See the
-- data constructor for a full description of this invariant.
-- Since CastTy cannot be nested, the result of discardCast
-- cannot be a CastTy.
discardCast :: Type -> Type
discardCast :: Type -> Type
discardCast (CastTy Type
ty KindCoercion
_) = ASSERT(not (isCastTy ty)) ty
  where
  isCastTy :: Type -> Bool
isCastTy CastTy{} = Bool
True
  isCastTy Type
_        = Bool
False
discardCast Type
ty            = Type
ty


{-
--------------------------------------------------------------------
                            CoercionTy
                            ~~~~~~~~~~
CoercionTy allows us to inject coercions into types. A CoercionTy
should appear only in the right-hand side of an application.
-}

mkCoercionTy :: Coercion -> Type
mkCoercionTy :: KindCoercion -> Type
mkCoercionTy = KindCoercion -> Type
CoercionTy

isCoercionTy :: Type -> Bool
isCoercionTy :: Type -> Bool
isCoercionTy (CoercionTy KindCoercion
_) = Bool
True
isCoercionTy Type
_              = Bool
False

isCoercionTy_maybe :: Type -> Maybe Coercion
isCoercionTy_maybe :: Type -> Maybe KindCoercion
isCoercionTy_maybe (CoercionTy KindCoercion
co) = KindCoercion -> Maybe KindCoercion
forall a. a -> Maybe a
Just KindCoercion
co
isCoercionTy_maybe Type
_               = Maybe KindCoercion
forall a. Maybe a
Nothing

stripCoercionTy :: Type -> Coercion
stripCoercionTy :: Type -> KindCoercion
stripCoercionTy (CoercionTy KindCoercion
co) = KindCoercion
co
stripCoercionTy Type
ty              = String -> SDoc -> KindCoercion
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"stripCoercionTy" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
ty)

{-
---------------------------------------------------------------------
                                SynTy
                                ~~~~~

Notes on type synonyms
~~~~~~~~~~~~~~~~~~~~~~
The various "split" functions (splitFunTy, splitRhoTy, splitForAllTy) try
to return type synonyms wherever possible. Thus

        type Foo a = a -> a

we want
        splitFunTys (a -> Foo a) = ([a], Foo a)
not                                ([a], a -> a)

The reason is that we then get better (shorter) type signatures in
interfaces.  Notably this plays a role in tcTySigs in TcBinds.hs.


---------------------------------------------------------------------
                                ForAllTy
                                ~~~~~~~~
-}

-- | Make a dependent forall over an 'Inferred' variable
mkTyCoInvForAllTy :: TyCoVar -> Type -> Type
mkTyCoInvForAllTy :: TyVar -> Type -> Type
mkTyCoInvForAllTy TyVar
tv Type
ty
  | TyVar -> Bool
isCoVar TyVar
tv
  , Bool -> Bool
not (TyVar
tv TyVar -> VarSet -> Bool
`elemVarSet` Type -> VarSet
tyCoVarsOfType Type
ty)
  = Type -> Type -> Type
mkVisFunTy (TyVar -> Type
varType TyVar
tv) Type
ty
  | Bool
otherwise
  = VarBndr TyVar ArgFlag -> Type -> Type
ForAllTy (TyVar -> ArgFlag -> VarBndr TyVar ArgFlag
forall var argf. var -> argf -> VarBndr var argf
Bndr TyVar
tv ArgFlag
Inferred) Type
ty

-- | Like 'mkTyCoInvForAllTy', but tv should be a tyvar
mkInvForAllTy :: TyVar -> Type -> Type
mkInvForAllTy :: TyVar -> Type -> Type
mkInvForAllTy TyVar
tv Type
ty = ASSERT( isTyVar tv )
                      VarBndr TyVar ArgFlag -> Type -> Type
ForAllTy (TyVar -> ArgFlag -> VarBndr TyVar ArgFlag
forall var argf. var -> argf -> VarBndr var argf
Bndr TyVar
tv ArgFlag
Inferred) Type
ty

-- | Like 'mkForAllTys', but assumes all variables are dependent and
-- 'Inferred', a common case
mkTyCoInvForAllTys :: [TyCoVar] -> Type -> Type
mkTyCoInvForAllTys :: [TyVar] -> Type -> Type
mkTyCoInvForAllTys [TyVar]
tvs Type
ty = (TyVar -> Type -> Type) -> Type -> [TyVar] -> Type
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr TyVar -> Type -> Type
mkTyCoInvForAllTy Type
ty [TyVar]
tvs

-- | Like 'mkTyCoInvForAllTys', but tvs should be a list of tyvar
mkInvForAllTys :: [TyVar] -> Type -> Type
mkInvForAllTys :: [TyVar] -> Type -> Type
mkInvForAllTys [TyVar]
tvs Type
ty = (TyVar -> Type -> Type) -> Type -> [TyVar] -> Type
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr TyVar -> Type -> Type
mkInvForAllTy Type
ty [TyVar]
tvs

-- | Like 'mkForAllTy', but assumes the variable is dependent and 'Specified',
-- a common case
mkSpecForAllTy :: TyVar -> Type -> Type
mkSpecForAllTy :: TyVar -> Type -> Type
mkSpecForAllTy TyVar
tv Type
ty = ASSERT( isTyVar tv )
                       -- covar is always Inferred, so input should be tyvar
                       VarBndr TyVar ArgFlag -> Type -> Type
ForAllTy (TyVar -> ArgFlag -> VarBndr TyVar ArgFlag
forall var argf. var -> argf -> VarBndr var argf
Bndr TyVar
tv ArgFlag
Specified) Type
ty

-- | Like 'mkForAllTys', but assumes all variables are dependent and
-- 'Specified', a common case
mkSpecForAllTys :: [TyVar] -> Type -> Type
mkSpecForAllTys :: [TyVar] -> Type -> Type
mkSpecForAllTys [TyVar]
tvs Type
ty = (TyVar -> Type -> Type) -> Type -> [TyVar] -> Type
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr TyVar -> Type -> Type
mkSpecForAllTy Type
ty [TyVar]
tvs

-- | Like mkForAllTys, but assumes all variables are dependent and visible
mkVisForAllTys :: [TyVar] -> Type -> Type
mkVisForAllTys :: [TyVar] -> Type -> Type
mkVisForAllTys [TyVar]
tvs = ASSERT( all isTyVar tvs )
                     -- covar is always Inferred, so all inputs should be tyvar
                     [VarBndr TyVar ArgFlag] -> Type -> Type
mkForAllTys [ TyVar -> ArgFlag -> VarBndr TyVar ArgFlag
forall var argf. var -> argf -> VarBndr var argf
Bndr TyVar
tv ArgFlag
Required | TyVar
tv <- [TyVar]
tvs ]

mkLamType  :: Var -> Type -> Type
-- ^ Makes a @(->)@ type or an implicit forall type, depending
-- on whether it is given a type variable or a term variable.
-- This is used, for example, when producing the type of a lambda.
-- Always uses Inferred binders.
mkLamTypes :: [Var] -> Type -> Type
-- ^ 'mkLamType' for multiple type or value arguments

mkLamType :: TyVar -> Type -> Type
mkLamType TyVar
v Type
body_ty
   | TyVar -> Bool
isTyVar TyVar
v
   = VarBndr TyVar ArgFlag -> Type -> Type
ForAllTy (TyVar -> ArgFlag -> VarBndr TyVar ArgFlag
forall var argf. var -> argf -> VarBndr var argf
Bndr TyVar
v ArgFlag
Inferred) Type
body_ty

   | TyVar -> Bool
isCoVar TyVar
v
   , TyVar
v TyVar -> VarSet -> Bool
`elemVarSet` Type -> VarSet
tyCoVarsOfType Type
body_ty
   = VarBndr TyVar ArgFlag -> Type -> Type
ForAllTy (TyVar -> ArgFlag -> VarBndr TyVar ArgFlag
forall var argf. var -> argf -> VarBndr var argf
Bndr TyVar
v ArgFlag
Required) Type
body_ty

   | HasDebugCallStack => Type -> Bool
Type -> Bool
isPredTy Type
arg_ty  -- See Note [mkLamType: dictionary arguments]
   = Type -> Type -> Type
mkInvisFunTy Type
arg_ty Type
body_ty

   | Bool
otherwise
   = Type -> Type -> Type
mkVisFunTy Type
arg_ty Type
body_ty
   where
     arg_ty :: Type
arg_ty = TyVar -> Type
varType TyVar
v

mkLamTypes :: [TyVar] -> Type -> Type
mkLamTypes [TyVar]
vs Type
ty = (TyVar -> Type -> Type) -> Type -> [TyVar] -> Type
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr TyVar -> Type -> Type
mkLamType Type
ty [TyVar]
vs

{- Note [mkLamType: dictionary arguments]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If we have (\ (d :: Ord a). blah), we want to give it type
           (Ord a => blah_ty)
with a fat arrow; that is, using mkInvisFunTy, not mkVisFunTy.

Why? After all, we are in Core, where (=>) and (->) behave the same.
Yes, but the /specialiser/ does treat dictionary arguments specially.
Suppose we do w/w on 'foo' in module A, thus (#11272, #6056)
   foo :: Ord a => Int -> blah
   foo a d x = case x of I# x' -> $wfoo @a d x'

   $wfoo :: Ord a => Int# -> blah

Now in module B we see (foo @Int dOrdInt).  The specialiser will
specialise this to $sfoo, where
   $sfoo :: Int -> blah
   $sfoo x = case x of I# x' -> $wfoo @Int dOrdInt x'

Now we /must/ also specialise $wfoo!  But it wasn't user-written,
and has a type built with mkLamTypes.

Conclusion: the easiest thing is to make mkLamType build
            (c => ty)
when the argument is a predicate type.  See TyCoRep
Note [Types for coercions, predicates, and evidence]
-}

-- | Given a list of type-level vars and the free vars of a result kind,
-- makes TyCoBinders, preferring anonymous binders
-- if the variable is, in fact, not dependent.
-- e.g.    mkTyConBindersPreferAnon [(k:*),(b:k),(c:k)] (k->k)
-- We want (k:*) Named, (b:k) Anon, (c:k) Anon
--
-- All non-coercion binders are /visible/.
mkTyConBindersPreferAnon :: [TyVar]      -- ^ binders
                         -> TyCoVarSet   -- ^ free variables of result
                         -> [TyConBinder]
mkTyConBindersPreferAnon :: [TyVar] -> VarSet -> [TyConBinder]
mkTyConBindersPreferAnon [TyVar]
vars VarSet
inner_tkvs = ASSERT( all isTyVar vars)
                                           ([TyConBinder], VarSet) -> [TyConBinder]
forall a b. (a, b) -> a
fst ([TyVar] -> ([TyConBinder], VarSet)
go [TyVar]
vars)
  where
    go :: [TyVar] -> ([TyConBinder], VarSet) -- also returns the free vars
    go :: [TyVar] -> ([TyConBinder], VarSet)
go [] = ([], VarSet
inner_tkvs)
    go (TyVar
v:[TyVar]
vs) | TyVar
v TyVar -> VarSet -> Bool
`elemVarSet` VarSet
fvs
              = ( TyVar -> TyConBndrVis -> TyConBinder
forall var argf. var -> argf -> VarBndr var argf
Bndr TyVar
v (ArgFlag -> TyConBndrVis
NamedTCB ArgFlag
Required) TyConBinder -> [TyConBinder] -> [TyConBinder]
forall a. a -> [a] -> [a]
: [TyConBinder]
binders
                , VarSet
fvs VarSet -> TyVar -> VarSet
`delVarSet` TyVar
v VarSet -> VarSet -> VarSet
`unionVarSet` VarSet
kind_vars )
              | Bool
otherwise
              = ( TyVar -> TyConBndrVis -> TyConBinder
forall var argf. var -> argf -> VarBndr var argf
Bndr TyVar
v (AnonArgFlag -> TyConBndrVis
AnonTCB AnonArgFlag
VisArg) TyConBinder -> [TyConBinder] -> [TyConBinder]
forall a. a -> [a] -> [a]
: [TyConBinder]
binders
                , VarSet
fvs VarSet -> VarSet -> VarSet
`unionVarSet` VarSet
kind_vars )
      where
        ([TyConBinder]
binders, VarSet
fvs) = [TyVar] -> ([TyConBinder], VarSet)
go [TyVar]
vs
        kind_vars :: VarSet
kind_vars      = Type -> VarSet
tyCoVarsOfType (Type -> VarSet) -> Type -> VarSet
forall a b. (a -> b) -> a -> b
$ TyVar -> Type
tyVarKind TyVar
v

-- | Take a ForAllTy apart, returning the list of tycovars and the result type.
-- This always succeeds, even if it returns only an empty list. Note that the
-- result type returned may have free variables that were bound by a forall.
splitForAllTys :: Type -> ([TyCoVar], Type)
splitForAllTys :: Type -> ([TyVar], Type)
splitForAllTys Type
ty = Type -> Type -> [TyVar] -> ([TyVar], Type)
split Type
ty Type
ty []
  where
    split :: Type -> Type -> [TyVar] -> ([TyVar], Type)
split Type
orig_ty Type
ty [TyVar]
tvs | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Type -> [TyVar] -> ([TyVar], Type)
split Type
orig_ty Type
ty' [TyVar]
tvs
    split Type
_       (ForAllTy (Bndr TyVar
tv ArgFlag
_) Type
ty)    [TyVar]
tvs = Type -> Type -> [TyVar] -> ([TyVar], Type)
split Type
ty Type
ty (TyVar
tvTyVar -> [TyVar] -> [TyVar]
forall a. a -> [a] -> [a]
:[TyVar]
tvs)
    split Type
orig_ty Type
_                            [TyVar]
tvs = ([TyVar] -> [TyVar]
forall a. [a] -> [a]
reverse [TyVar]
tvs, Type
orig_ty)

-- | Like 'splitForAllTys', but only splits a 'ForAllTy' if
-- @'sameVis' argf supplied_argf@ is 'True', where @argf@ is the visibility
-- of the @ForAllTy@'s binder and @supplied_argf@ is the visibility provided
-- as an argument to this function.
splitForAllTysSameVis :: ArgFlag -> Type -> ([TyCoVar], Type)
splitForAllTysSameVis :: ArgFlag -> Type -> ([TyVar], Type)
splitForAllTysSameVis ArgFlag
supplied_argf Type
ty = Type -> Type -> [TyVar] -> ([TyVar], Type)
split Type
ty Type
ty []
  where
    split :: Type -> Type -> [TyVar] -> ([TyVar], Type)
split Type
orig_ty Type
ty [TyVar]
tvs | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Type -> [TyVar] -> ([TyVar], Type)
split Type
orig_ty Type
ty' [TyVar]
tvs
    split Type
_       (ForAllTy (Bndr TyVar
tv ArgFlag
argf) Type
ty) [TyVar]
tvs
      | ArgFlag
argf ArgFlag -> ArgFlag -> Bool
`sameVis` ArgFlag
supplied_argf               = Type -> Type -> [TyVar] -> ([TyVar], Type)
split Type
ty Type
ty (TyVar
tvTyVar -> [TyVar] -> [TyVar]
forall a. a -> [a] -> [a]
:[TyVar]
tvs)
    split Type
orig_ty Type
_                            [TyVar]
tvs = ([TyVar] -> [TyVar]
forall a. [a] -> [a]
reverse [TyVar]
tvs, Type
orig_ty)

-- | Like splitForAllTys, but split only for tyvars.
-- This always succeeds, even if it returns only an empty list. Note that the
-- result type returned may have free variables that were bound by a forall.
splitTyVarForAllTys :: Type -> ([TyVar], Type)
splitTyVarForAllTys :: Type -> ([TyVar], Type)
splitTyVarForAllTys Type
ty = Type -> Type -> [TyVar] -> ([TyVar], Type)
split Type
ty Type
ty []
  where
    split :: Type -> Type -> [TyVar] -> ([TyVar], Type)
split Type
orig_ty Type
ty [TyVar]
tvs | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty     = Type -> Type -> [TyVar] -> ([TyVar], Type)
split Type
orig_ty Type
ty' [TyVar]
tvs
    split Type
_ (ForAllTy (Bndr TyVar
tv ArgFlag
_) Type
ty) [TyVar]
tvs | TyVar -> Bool
isTyVar TyVar
tv = Type -> Type -> [TyVar] -> ([TyVar], Type)
split Type
ty Type
ty (TyVar
tvTyVar -> [TyVar] -> [TyVar]
forall a. a -> [a] -> [a]
:[TyVar]
tvs)
    split Type
orig_ty Type
_                   [TyVar]
tvs              = ([TyVar] -> [TyVar]
forall a. [a] -> [a]
reverse [TyVar]
tvs, Type
orig_ty)

-- | Checks whether this is a proper forall (with a named binder)
isForAllTy :: Type -> Bool
isForAllTy :: Type -> Bool
isForAllTy Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Bool
isForAllTy Type
ty'
isForAllTy (ForAllTy {}) = Bool
True
isForAllTy Type
_             = Bool
False

-- | Like `isForAllTy`, but returns True only if it is a tyvar binder
isForAllTy_ty :: Type -> Bool
isForAllTy_ty :: Type -> Bool
isForAllTy_ty Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Bool
isForAllTy_ty Type
ty'
isForAllTy_ty (ForAllTy (Bndr TyVar
tv ArgFlag
_) Type
_) | TyVar -> Bool
isTyVar TyVar
tv = Bool
True
isForAllTy_ty Type
_             = Bool
False

-- | Like `isForAllTy`, but returns True only if it is a covar binder
isForAllTy_co :: Type -> Bool
isForAllTy_co :: Type -> Bool
isForAllTy_co Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Bool
isForAllTy_co Type
ty'
isForAllTy_co (ForAllTy (Bndr TyVar
tv ArgFlag
_) Type
_) | TyVar -> Bool
isCoVar TyVar
tv = Bool
True
isForAllTy_co Type
_             = Bool
False

-- | Is this a function or forall?
isPiTy :: Type -> Bool
isPiTy :: Type -> Bool
isPiTy Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Bool
isPiTy Type
ty'
isPiTy (ForAllTy {}) = Bool
True
isPiTy (FunTy {})    = Bool
True
isPiTy Type
_             = Bool
False

-- | Is this a function?
isFunTy :: Type -> Bool
isFunTy :: Type -> Bool
isFunTy Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Bool
isFunTy Type
ty'
isFunTy (FunTy {}) = Bool
True
isFunTy Type
_          = Bool
False

-- | Take a forall type apart, or panics if that is not possible.
splitForAllTy :: Type -> (TyCoVar, Type)
splitForAllTy :: Type -> (TyVar, Type)
splitForAllTy Type
ty
  | Just (TyVar, Type)
answer <- Type -> Maybe (TyVar, Type)
splitForAllTy_maybe Type
ty = (TyVar, Type)
answer
  | Bool
otherwise                             = String -> SDoc -> (TyVar, Type)
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"splitForAllTy" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
ty)

-- | Drops all ForAllTys
dropForAlls :: Type -> Type
dropForAlls :: Type -> Type
dropForAlls Type
ty = Type -> Type
go Type
ty
  where
    go :: Type -> Type
go Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Type
go Type
ty'
    go (ForAllTy VarBndr TyVar ArgFlag
_ Type
res)            = Type -> Type
go Type
res
    go Type
res                         = Type
res

-- | Attempts to take a forall type apart, but only if it's a proper forall,
-- with a named binder
splitForAllTy_maybe :: Type -> Maybe (TyCoVar, Type)
splitForAllTy_maybe :: Type -> Maybe (TyVar, Type)
splitForAllTy_maybe Type
ty = Type -> Maybe (TyVar, Type)
go Type
ty
  where
    go :: Type -> Maybe (TyVar, Type)
go Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Maybe (TyVar, Type)
go Type
ty'
    go (ForAllTy (Bndr TyVar
tv ArgFlag
_) Type
ty)    = (TyVar, Type) -> Maybe (TyVar, Type)
forall a. a -> Maybe a
Just (TyVar
tv, Type
ty)
    go Type
_                            = Maybe (TyVar, Type)
forall a. Maybe a
Nothing

-- | Like splitForAllTy_maybe, but only returns Just if it is a tyvar binder.
splitForAllTy_ty_maybe :: Type -> Maybe (TyCoVar, Type)
splitForAllTy_ty_maybe :: Type -> Maybe (TyVar, Type)
splitForAllTy_ty_maybe Type
ty = Type -> Maybe (TyVar, Type)
go Type
ty
  where
    go :: Type -> Maybe (TyVar, Type)
go Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Maybe (TyVar, Type)
go Type
ty'
    go (ForAllTy (Bndr TyVar
tv ArgFlag
_) Type
ty) | TyVar -> Bool
isTyVar TyVar
tv = (TyVar, Type) -> Maybe (TyVar, Type)
forall a. a -> Maybe a
Just (TyVar
tv, Type
ty)
    go Type
_                            = Maybe (TyVar, Type)
forall a. Maybe a
Nothing

-- | Like splitForAllTy_maybe, but only returns Just if it is a covar binder.
splitForAllTy_co_maybe :: Type -> Maybe (TyCoVar, Type)
splitForAllTy_co_maybe :: Type -> Maybe (TyVar, Type)
splitForAllTy_co_maybe Type
ty = Type -> Maybe (TyVar, Type)
go Type
ty
  where
    go :: Type -> Maybe (TyVar, Type)
go Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Maybe (TyVar, Type)
go Type
ty'
    go (ForAllTy (Bndr TyVar
tv ArgFlag
_) Type
ty) | TyVar -> Bool
isCoVar TyVar
tv = (TyVar, Type) -> Maybe (TyVar, Type)
forall a. a -> Maybe a
Just (TyVar
tv, Type
ty)
    go Type
_                            = Maybe (TyVar, Type)
forall a. Maybe a
Nothing

-- | Attempts to take a forall type apart; works with proper foralls and
-- functions
splitPiTy_maybe :: Type -> Maybe (TyCoBinder, Type)
splitPiTy_maybe :: Type -> Maybe (TyCoBinder, Type)
splitPiTy_maybe Type
ty = Type -> Maybe (TyCoBinder, Type)
go Type
ty
  where
    go :: Type -> Maybe (TyCoBinder, Type)
go Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Maybe (TyCoBinder, Type)
go Type
ty'
    go (ForAllTy VarBndr TyVar ArgFlag
bndr Type
ty) = (TyCoBinder, Type) -> Maybe (TyCoBinder, Type)
forall a. a -> Maybe a
Just (VarBndr TyVar ArgFlag -> TyCoBinder
Named VarBndr TyVar ArgFlag
bndr, Type
ty)
    go (FunTy { ft_af :: Type -> AnonArgFlag
ft_af = AnonArgFlag
af, ft_arg :: Type -> Type
ft_arg = Type
arg, ft_res :: Type -> Type
ft_res = Type
res})
                          = (TyCoBinder, Type) -> Maybe (TyCoBinder, Type)
forall a. a -> Maybe a
Just (AnonArgFlag -> Type -> TyCoBinder
Anon AnonArgFlag
af Type
arg, Type
res)
    go Type
_                  = Maybe (TyCoBinder, Type)
forall a. Maybe a
Nothing

-- | Takes a forall type apart, or panics
splitPiTy :: Type -> (TyCoBinder, Type)
splitPiTy :: Type -> (TyCoBinder, Type)
splitPiTy Type
ty
  | Just (TyCoBinder, Type)
answer <- Type -> Maybe (TyCoBinder, Type)
splitPiTy_maybe Type
ty = (TyCoBinder, Type)
answer
  | Bool
otherwise                         = String -> SDoc -> (TyCoBinder, Type)
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"splitPiTy" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
ty)

-- | Split off all TyCoBinders to a type, splitting both proper foralls
-- and functions
splitPiTys :: Type -> ([TyCoBinder], Type)
splitPiTys :: Type -> ([TyCoBinder], Type)
splitPiTys Type
ty = Type -> Type -> [TyCoBinder] -> ([TyCoBinder], Type)
split Type
ty Type
ty []
  where
    split :: Type -> Type -> [TyCoBinder] -> ([TyCoBinder], Type)
split Type
orig_ty Type
ty [TyCoBinder]
bs | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Type -> [TyCoBinder] -> ([TyCoBinder], Type)
split Type
orig_ty Type
ty' [TyCoBinder]
bs
    split Type
_       (ForAllTy VarBndr TyVar ArgFlag
b Type
res) [TyCoBinder]
bs = Type -> Type -> [TyCoBinder] -> ([TyCoBinder], Type)
split Type
res Type
res (VarBndr TyVar ArgFlag -> TyCoBinder
Named VarBndr TyVar ArgFlag
b  TyCoBinder -> [TyCoBinder] -> [TyCoBinder]
forall a. a -> [a] -> [a]
: [TyCoBinder]
bs)
    split Type
_       (FunTy { ft_af :: Type -> AnonArgFlag
ft_af = AnonArgFlag
af, ft_arg :: Type -> Type
ft_arg = Type
arg, ft_res :: Type -> Type
ft_res = Type
res }) [TyCoBinder]
bs
                                      = Type -> Type -> [TyCoBinder] -> ([TyCoBinder], Type)
split Type
res Type
res (AnonArgFlag -> Type -> TyCoBinder
Anon AnonArgFlag
af Type
arg TyCoBinder -> [TyCoBinder] -> [TyCoBinder]
forall a. a -> [a] -> [a]
: [TyCoBinder]
bs)
    split Type
orig_ty Type
_                [TyCoBinder]
bs = ([TyCoBinder] -> [TyCoBinder]
forall a. [a] -> [a]
reverse [TyCoBinder]
bs, Type
orig_ty)

-- | Like 'splitPiTys' but split off only /named/ binders
--   and returns TyCoVarBinders rather than TyCoBinders
splitForAllVarBndrs :: Type -> ([TyCoVarBinder], Type)
splitForAllVarBndrs :: Type -> ([VarBndr TyVar ArgFlag], Type)
splitForAllVarBndrs Type
ty = Type
-> Type
-> [VarBndr TyVar ArgFlag]
-> ([VarBndr TyVar ArgFlag], Type)
split Type
ty Type
ty []
  where
    split :: Type
-> Type
-> [VarBndr TyVar ArgFlag]
-> ([VarBndr TyVar ArgFlag], Type)
split Type
orig_ty Type
ty [VarBndr TyVar ArgFlag]
bs | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type
-> Type
-> [VarBndr TyVar ArgFlag]
-> ([VarBndr TyVar ArgFlag], Type)
split Type
orig_ty Type
ty' [VarBndr TyVar ArgFlag]
bs
    split Type
_       (ForAllTy VarBndr TyVar ArgFlag
b Type
res) [VarBndr TyVar ArgFlag]
bs = Type
-> Type
-> [VarBndr TyVar ArgFlag]
-> ([VarBndr TyVar ArgFlag], Type)
split Type
res Type
res (VarBndr TyVar ArgFlag
bVarBndr TyVar ArgFlag
-> [VarBndr TyVar ArgFlag] -> [VarBndr TyVar ArgFlag]
forall a. a -> [a] -> [a]
:[VarBndr TyVar ArgFlag]
bs)
    split Type
orig_ty Type
_                [VarBndr TyVar ArgFlag]
bs = ([VarBndr TyVar ArgFlag] -> [VarBndr TyVar ArgFlag]
forall a. [a] -> [a]
reverse [VarBndr TyVar ArgFlag]
bs, Type
orig_ty)
{-# INLINE splitForAllVarBndrs #-}

invisibleTyBndrCount :: Type -> Int
-- Returns the number of leading invisible forall'd binders in the type
-- Includes invisible predicate arguments; e.g. for
--    e.g.  forall {k}. (k ~ *) => k -> k
-- returns 2 not 1
invisibleTyBndrCount :: Type -> Int
invisibleTyBndrCount Type
ty = [TyCoBinder] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length (([TyCoBinder], Type) -> [TyCoBinder]
forall a b. (a, b) -> a
fst (Type -> ([TyCoBinder], Type)
splitPiTysInvisible Type
ty))

-- Like splitPiTys, but returns only *invisible* binders, including constraints
-- Stops at the first visible binder
splitPiTysInvisible :: Type -> ([TyCoBinder], Type)
splitPiTysInvisible :: Type -> ([TyCoBinder], Type)
splitPiTysInvisible Type
ty = Type -> Type -> [TyCoBinder] -> ([TyCoBinder], Type)
split Type
ty Type
ty []
   where
    split :: Type -> Type -> [TyCoBinder] -> ([TyCoBinder], Type)
split Type
orig_ty Type
ty [TyCoBinder]
bs
      | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty  = Type -> Type -> [TyCoBinder] -> ([TyCoBinder], Type)
split Type
orig_ty Type
ty' [TyCoBinder]
bs
    split Type
_ (ForAllTy VarBndr TyVar ArgFlag
b Type
res) [TyCoBinder]
bs
      | Bndr TyVar
_ ArgFlag
vis <- VarBndr TyVar ArgFlag
b
      , ArgFlag -> Bool
isInvisibleArgFlag ArgFlag
vis   = Type -> Type -> [TyCoBinder] -> ([TyCoBinder], Type)
split Type
res Type
res (VarBndr TyVar ArgFlag -> TyCoBinder
Named VarBndr TyVar ArgFlag
b  TyCoBinder -> [TyCoBinder] -> [TyCoBinder]
forall a. a -> [a] -> [a]
: [TyCoBinder]
bs)
    split Type
_ (FunTy { ft_af :: Type -> AnonArgFlag
ft_af = AnonArgFlag
InvisArg, ft_arg :: Type -> Type
ft_arg = Type
arg, ft_res :: Type -> Type
ft_res = Type
res })  [TyCoBinder]
bs
                                 = Type -> Type -> [TyCoBinder] -> ([TyCoBinder], Type)
split Type
res Type
res (AnonArgFlag -> Type -> TyCoBinder
Anon AnonArgFlag
InvisArg Type
arg TyCoBinder -> [TyCoBinder] -> [TyCoBinder]
forall a. a -> [a] -> [a]
: [TyCoBinder]
bs)
    split Type
orig_ty Type
_          [TyCoBinder]
bs  = ([TyCoBinder] -> [TyCoBinder]
forall a. [a] -> [a]
reverse [TyCoBinder]
bs, Type
orig_ty)

splitPiTysInvisibleN :: Int -> Type -> ([TyCoBinder], Type)
-- Same as splitPiTysInvisible, but stop when
--   - you have found 'n' TyCoBinders,
--   - or you run out of invisible binders
splitPiTysInvisibleN :: Int -> Type -> ([TyCoBinder], Type)
splitPiTysInvisibleN Int
n Type
ty = Int -> Type -> Type -> [TyCoBinder] -> ([TyCoBinder], Type)
forall a.
(Eq a, Num a) =>
a -> Type -> Type -> [TyCoBinder] -> ([TyCoBinder], Type)
split Int
n Type
ty Type
ty []
   where
    split :: a -> Type -> Type -> [TyCoBinder] -> ([TyCoBinder], Type)
split a
n Type
orig_ty Type
ty [TyCoBinder]
bs
      | a
n a -> a -> Bool
forall a. Eq a => a -> a -> Bool
== a
0                  = ([TyCoBinder] -> [TyCoBinder]
forall a. [a] -> [a]
reverse [TyCoBinder]
bs, Type
orig_ty)
      | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = a -> Type -> Type -> [TyCoBinder] -> ([TyCoBinder], Type)
split a
n Type
orig_ty Type
ty' [TyCoBinder]
bs
      | ForAllTy VarBndr TyVar ArgFlag
b Type
res <- Type
ty
      , Bndr TyVar
_ ArgFlag
vis <- VarBndr TyVar ArgFlag
b
      , ArgFlag -> Bool
isInvisibleArgFlag ArgFlag
vis  = a -> Type -> Type -> [TyCoBinder] -> ([TyCoBinder], Type)
split (a
na -> a -> a
forall a. Num a => a -> a -> a
-a
1) Type
res Type
res (VarBndr TyVar ArgFlag -> TyCoBinder
Named VarBndr TyVar ArgFlag
b  TyCoBinder -> [TyCoBinder] -> [TyCoBinder]
forall a. a -> [a] -> [a]
: [TyCoBinder]
bs)
      | FunTy { ft_af :: Type -> AnonArgFlag
ft_af = AnonArgFlag
InvisArg, ft_arg :: Type -> Type
ft_arg = Type
arg, ft_res :: Type -> Type
ft_res = Type
res } <- Type
ty
                                = a -> Type -> Type -> [TyCoBinder] -> ([TyCoBinder], Type)
split (a
na -> a -> a
forall a. Num a => a -> a -> a
-a
1) Type
res Type
res (AnonArgFlag -> Type -> TyCoBinder
Anon AnonArgFlag
InvisArg Type
arg TyCoBinder -> [TyCoBinder] -> [TyCoBinder]
forall a. a -> [a] -> [a]
: [TyCoBinder]
bs)
      | Bool
otherwise               = ([TyCoBinder] -> [TyCoBinder]
forall a. [a] -> [a]
reverse [TyCoBinder]
bs, Type
orig_ty)

-- | Given a 'TyCon' and a list of argument types, filter out any invisible
-- (i.e., 'Inferred' or 'Specified') arguments.
filterOutInvisibleTypes :: TyCon -> [Type] -> [Type]
filterOutInvisibleTypes :: TyCon -> [Type] -> [Type]
filterOutInvisibleTypes TyCon
tc [Type]
tys = ([Type], [Type]) -> [Type]
forall a b. (a, b) -> b
snd (([Type], [Type]) -> [Type]) -> ([Type], [Type]) -> [Type]
forall a b. (a -> b) -> a -> b
$ TyCon -> [Type] -> ([Type], [Type])
partitionInvisibleTypes TyCon
tc [Type]
tys

-- | Given a 'TyCon' and a list of argument types, filter out any 'Inferred'
-- arguments.
filterOutInferredTypes :: TyCon -> [Type] -> [Type]
filterOutInferredTypes :: TyCon -> [Type] -> [Type]
filterOutInferredTypes TyCon
tc [Type]
tys =
  [Bool] -> [Type] -> [Type]
forall a. [Bool] -> [a] -> [a]
filterByList ((ArgFlag -> Bool) -> [ArgFlag] -> [Bool]
forall a b. (a -> b) -> [a] -> [b]
map (ArgFlag -> ArgFlag -> Bool
forall a. Eq a => a -> a -> Bool
/= ArgFlag
Inferred) ([ArgFlag] -> [Bool]) -> [ArgFlag] -> [Bool]
forall a b. (a -> b) -> a -> b
$ TyCon -> [Type] -> [ArgFlag]
tyConArgFlags TyCon
tc [Type]
tys) [Type]
tys

-- | Given a 'TyCon' and a list of argument types, partition the arguments
-- into:
--
-- 1. 'Inferred' or 'Specified' (i.e., invisible) arguments and
--
-- 2. 'Required' (i.e., visible) arguments
partitionInvisibleTypes :: TyCon -> [Type] -> ([Type], [Type])
partitionInvisibleTypes :: TyCon -> [Type] -> ([Type], [Type])
partitionInvisibleTypes TyCon
tc [Type]
tys =
  [Bool] -> [Type] -> ([Type], [Type])
forall a. [Bool] -> [a] -> ([a], [a])
partitionByList ((ArgFlag -> Bool) -> [ArgFlag] -> [Bool]
forall a b. (a -> b) -> [a] -> [b]
map ArgFlag -> Bool
isInvisibleArgFlag ([ArgFlag] -> [Bool]) -> [ArgFlag] -> [Bool]
forall a b. (a -> b) -> a -> b
$ TyCon -> [Type] -> [ArgFlag]
tyConArgFlags TyCon
tc [Type]
tys) [Type]
tys

-- | Given a list of things paired with their visibilities, partition the
-- things into (invisible things, visible things).
partitionInvisibles :: [(a, ArgFlag)] -> ([a], [a])
partitionInvisibles :: [(a, ArgFlag)] -> ([a], [a])
partitionInvisibles = ((a, ArgFlag) -> Either a a) -> [(a, ArgFlag)] -> ([a], [a])
forall a b c. (a -> Either b c) -> [a] -> ([b], [c])
partitionWith (a, ArgFlag) -> Either a a
forall a. (a, ArgFlag) -> Either a a
pick_invis
  where
    pick_invis :: (a, ArgFlag) -> Either a a
    pick_invis :: (a, ArgFlag) -> Either a a
pick_invis (a
thing, ArgFlag
vis) | ArgFlag -> Bool
isInvisibleArgFlag ArgFlag
vis = a -> Either a a
forall a b. a -> Either a b
Left a
thing
                            | Bool
otherwise              = a -> Either a a
forall a b. b -> Either a b
Right a
thing

-- | Given a 'TyCon' and a list of argument types to which the 'TyCon' is
-- applied, determine each argument's visibility
-- ('Inferred', 'Specified', or 'Required').
--
-- Wrinkle: consider the following scenario:
--
-- > T :: forall k. k -> k
-- > tyConArgFlags T [forall m. m -> m -> m, S, R, Q]
--
-- After substituting, we get
--
-- > T (forall m. m -> m -> m) :: (forall m. m -> m -> m) -> forall n. n -> n -> n
--
-- Thus, the first argument is invisible, @S@ is visible, @R@ is invisible again,
-- and @Q@ is visible.
tyConArgFlags :: TyCon -> [Type] -> [ArgFlag]
tyConArgFlags :: TyCon -> [Type] -> [ArgFlag]
tyConArgFlags TyCon
tc = Type -> [Type] -> [ArgFlag]
fun_kind_arg_flags (TyCon -> Type
tyConKind TyCon
tc)

-- | Given a 'Type' and a list of argument types to which the 'Type' is
-- applied, determine each argument's visibility
-- ('Inferred', 'Specified', or 'Required').
--
-- Most of the time, the arguments will be 'Required', but not always. Consider
-- @f :: forall a. a -> Type@. In @f Type Bool@, the first argument (@Type@) is
-- 'Specified' and the second argument (@Bool@) is 'Required'. It is precisely
-- this sort of higher-rank situation in which 'appTyArgFlags' comes in handy,
-- since @f Type Bool@ would be represented in Core using 'AppTy's.
-- (See also #15792).
appTyArgFlags :: Type -> [Type] -> [ArgFlag]
appTyArgFlags :: Type -> [Type] -> [ArgFlag]
appTyArgFlags Type
ty = Type -> [Type] -> [ArgFlag]
fun_kind_arg_flags (HasDebugCallStack => Type -> Type
Type -> Type
typeKind Type
ty)

-- | Given a function kind and a list of argument types (where each argument's
-- kind aligns with the corresponding position in the argument kind), determine
-- each argument's visibility ('Inferred', 'Specified', or 'Required').
fun_kind_arg_flags :: Kind -> [Type] -> [ArgFlag]
fun_kind_arg_flags :: Type -> [Type] -> [ArgFlag]
fun_kind_arg_flags = TCvSubst -> Type -> [Type] -> [ArgFlag]
go TCvSubst
emptyTCvSubst
  where
    go :: TCvSubst -> Type -> [Type] -> [ArgFlag]
go TCvSubst
subst Type
ki [Type]
arg_tys
      | Just Type
ki' <- Type -> Maybe Type
coreView Type
ki = TCvSubst -> Type -> [Type] -> [ArgFlag]
go TCvSubst
subst Type
ki' [Type]
arg_tys
    go TCvSubst
_ Type
_ [] = []
    go TCvSubst
subst (ForAllTy (Bndr TyVar
tv ArgFlag
argf) Type
res_ki) (Type
arg_ty:[Type]
arg_tys)
      = ArgFlag
argf ArgFlag -> [ArgFlag] -> [ArgFlag]
forall a. a -> [a] -> [a]
: TCvSubst -> Type -> [Type] -> [ArgFlag]
go TCvSubst
subst' Type
res_ki [Type]
arg_tys
      where
        subst' :: TCvSubst
subst' = TCvSubst -> TyVar -> Type -> TCvSubst
extendTvSubst TCvSubst
subst TyVar
tv Type
arg_ty
    go TCvSubst
subst (TyVarTy TyVar
tv) [Type]
arg_tys
      | Just Type
ki <- TCvSubst -> TyVar -> Maybe Type
lookupTyVar TCvSubst
subst TyVar
tv = TCvSubst -> Type -> [Type] -> [ArgFlag]
go TCvSubst
subst Type
ki [Type]
arg_tys
    -- This FunTy case is important to handle kinds with nested foralls, such
    -- as this kind (inspired by #16518):
    --
    --   forall {k1} k2. k1 -> k2 -> forall k3. k3 -> Type
    --
    -- Here, we want to get the following ArgFlags:
    --
    -- [Inferred,   Specified, Required, Required, Specified, Required]
    -- forall {k1}. forall k2. k1 ->     k2 ->     forall k3. k3 ->     Type
    go TCvSubst
subst (FunTy{ft_af :: Type -> AnonArgFlag
ft_af = AnonArgFlag
af, ft_res :: Type -> Type
ft_res = Type
res_ki}) (Type
_:[Type]
arg_tys)
      = ArgFlag
argf ArgFlag -> [ArgFlag] -> [ArgFlag]
forall a. a -> [a] -> [a]
: TCvSubst -> Type -> [Type] -> [ArgFlag]
go TCvSubst
subst Type
res_ki [Type]
arg_tys
      where
        argf :: ArgFlag
argf = case AnonArgFlag
af of
                 AnonArgFlag
VisArg   -> ArgFlag
Required
                 AnonArgFlag
InvisArg -> ArgFlag
Inferred
    go TCvSubst
_ Type
_ [Type]
arg_tys = (Type -> ArgFlag) -> [Type] -> [ArgFlag]
forall a b. (a -> b) -> [a] -> [b]
map (ArgFlag -> Type -> ArgFlag
forall a b. a -> b -> a
const ArgFlag
Required) [Type]
arg_tys
                        -- something is ill-kinded. But this can happen
                        -- when printing errors. Assume everything is Required.

-- @isTauTy@ tests if a type has no foralls
isTauTy :: Type -> Bool
isTauTy :: Type -> Bool
isTauTy Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Bool
isTauTy Type
ty'
isTauTy (TyVarTy TyVar
_)           = Bool
True
isTauTy (LitTy {})            = Bool
True
isTauTy (TyConApp TyCon
tc [Type]
tys)     = (Type -> Bool) -> [Type] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
all Type -> Bool
isTauTy [Type]
tys Bool -> Bool -> Bool
&& TyCon -> Bool
isTauTyCon TyCon
tc
isTauTy (AppTy Type
a Type
b)           = Type -> Bool
isTauTy Type
a Bool -> Bool -> Bool
&& Type -> Bool
isTauTy Type
b
isTauTy (FunTy AnonArgFlag
_ Type
a Type
b)         = Type -> Bool
isTauTy Type
a Bool -> Bool -> Bool
&& Type -> Bool
isTauTy Type
b
isTauTy (ForAllTy {})         = Bool
False
isTauTy (CastTy Type
ty KindCoercion
_)         = Type -> Bool
isTauTy Type
ty
isTauTy (CoercionTy KindCoercion
_)        = Bool
False  -- Not sure about this

{-
%************************************************************************
%*                                                                      *
   TyCoBinders
%*                                                                      *
%************************************************************************
-}

-- | Make an anonymous binder
mkAnonBinder :: AnonArgFlag -> Type -> TyCoBinder
mkAnonBinder :: AnonArgFlag -> Type -> TyCoBinder
mkAnonBinder = AnonArgFlag -> Type -> TyCoBinder
Anon

-- | Does this binder bind a variable that is /not/ erased? Returns
-- 'True' for anonymous binders.
isAnonTyCoBinder :: TyCoBinder -> Bool
isAnonTyCoBinder :: TyCoBinder -> Bool
isAnonTyCoBinder (Named {}) = Bool
False
isAnonTyCoBinder (Anon {})  = Bool
True

tyCoBinderVar_maybe :: TyCoBinder -> Maybe TyCoVar
tyCoBinderVar_maybe :: TyCoBinder -> Maybe TyVar
tyCoBinderVar_maybe (Named VarBndr TyVar ArgFlag
tv) = TyVar -> Maybe TyVar
forall a. a -> Maybe a
Just (TyVar -> Maybe TyVar) -> TyVar -> Maybe TyVar
forall a b. (a -> b) -> a -> b
$ VarBndr TyVar ArgFlag -> TyVar
forall tv argf. VarBndr tv argf -> tv
binderVar VarBndr TyVar ArgFlag
tv
tyCoBinderVar_maybe TyCoBinder
_          = Maybe TyVar
forall a. Maybe a
Nothing

tyCoBinderType :: TyCoBinder -> Type
tyCoBinderType :: TyCoBinder -> Type
tyCoBinderType (Named VarBndr TyVar ArgFlag
tvb) = VarBndr TyVar ArgFlag -> Type
forall argf. VarBndr TyVar argf -> Type
binderType VarBndr TyVar ArgFlag
tvb
tyCoBinderType (Anon AnonArgFlag
_ Type
ty) = Type
ty

tyBinderType :: TyBinder -> Type
tyBinderType :: TyCoBinder -> Type
tyBinderType (Named (Bndr TyVar
tv ArgFlag
_))
  = ASSERT( isTyVar tv )
    TyVar -> Type
tyVarKind TyVar
tv
tyBinderType (Anon AnonArgFlag
_ Type
ty)   = Type
ty

-- | Extract a relevant type, if there is one.
binderRelevantType_maybe :: TyCoBinder -> Maybe Type
binderRelevantType_maybe :: TyCoBinder -> Maybe Type
binderRelevantType_maybe (Named {})  = Maybe Type
forall a. Maybe a
Nothing
binderRelevantType_maybe (Anon AnonArgFlag
_ Type
ty) = Type -> Maybe Type
forall a. a -> Maybe a
Just Type
ty

------------- Closing over kinds -----------------

-- | Add the kind variables free in the kinds of the tyvars in the given set.
-- Returns a non-deterministic set.
closeOverKinds :: TyVarSet -> TyVarSet
closeOverKinds :: VarSet -> VarSet
closeOverKinds = FV -> VarSet
fvVarSet (FV -> VarSet) -> (VarSet -> FV) -> VarSet -> VarSet
forall b c a. (b -> c) -> (a -> b) -> a -> c
. [TyVar] -> FV
closeOverKindsFV ([TyVar] -> FV) -> (VarSet -> [TyVar]) -> VarSet -> FV
forall b c a. (b -> c) -> (a -> b) -> a -> c
. VarSet -> [TyVar]
forall elt. UniqSet elt -> [elt]
nonDetEltsUniqSet
  -- It's OK to use nonDetEltsUniqSet here because we immediately forget
  -- about the ordering by returning a set.

-- | Given a list of tyvars returns a deterministic FV computation that
-- returns the given tyvars with the kind variables free in the kinds of the
-- given tyvars.
closeOverKindsFV :: [TyVar] -> FV
closeOverKindsFV :: [TyVar] -> FV
closeOverKindsFV [TyVar]
tvs =
  (TyVar -> FV) -> [TyVar] -> FV
forall a. (a -> FV) -> [a] -> FV
mapUnionFV (Type -> FV
tyCoFVsOfType (Type -> FV) -> (TyVar -> Type) -> TyVar -> FV
forall b c a. (b -> c) -> (a -> b) -> a -> c
. TyVar -> Type
tyVarKind) [TyVar]
tvs FV -> FV -> FV
`unionFV` [TyVar] -> FV
mkFVs [TyVar]
tvs

-- | Add the kind variables free in the kinds of the tyvars in the given set.
-- Returns a deterministically ordered list.
closeOverKindsList :: [TyVar] -> [TyVar]
closeOverKindsList :: [TyVar] -> [TyVar]
closeOverKindsList [TyVar]
tvs = FV -> [TyVar]
fvVarList (FV -> [TyVar]) -> FV -> [TyVar]
forall a b. (a -> b) -> a -> b
$ [TyVar] -> FV
closeOverKindsFV [TyVar]
tvs

-- | Add the kind variables free in the kinds of the tyvars in the given set.
-- Returns a deterministic set.
closeOverKindsDSet :: DTyVarSet -> DTyVarSet
closeOverKindsDSet :: DTyVarSet -> DTyVarSet
closeOverKindsDSet = FV -> DTyVarSet
fvDVarSet (FV -> DTyVarSet) -> (DTyVarSet -> FV) -> DTyVarSet -> DTyVarSet
forall b c a. (b -> c) -> (a -> b) -> a -> c
. [TyVar] -> FV
closeOverKindsFV ([TyVar] -> FV) -> (DTyVarSet -> [TyVar]) -> DTyVarSet -> FV
forall b c a. (b -> c) -> (a -> b) -> a -> c
. DTyVarSet -> [TyVar]
dVarSetElems

{-
************************************************************************
*                                                                      *
\subsection{Type families}
*                                                                      *
************************************************************************
-}

mkFamilyTyConApp :: TyCon -> [Type] -> Type
-- ^ Given a family instance TyCon and its arg types, return the
-- corresponding family type.  E.g:
--
-- > data family T a
-- > data instance T (Maybe b) = MkT b
--
-- Where the instance tycon is :RTL, so:
--
-- > mkFamilyTyConApp :RTL Int  =  T (Maybe Int)
mkFamilyTyConApp :: TyCon -> [Type] -> Type
mkFamilyTyConApp TyCon
tc [Type]
tys
  | Just (TyCon
fam_tc, [Type]
fam_tys) <- TyCon -> Maybe (TyCon, [Type])
tyConFamInst_maybe TyCon
tc
  , let tvs :: [TyVar]
tvs = TyCon -> [TyVar]
tyConTyVars TyCon
tc
        fam_subst :: TCvSubst
fam_subst = ASSERT2( tvs `equalLength` tys, ppr tc <+> ppr tys )
                    [TyVar] -> [Type] -> TCvSubst
HasDebugCallStack => [TyVar] -> [Type] -> TCvSubst
zipTvSubst [TyVar]
tvs [Type]
tys
  = TyCon -> [Type] -> Type
mkTyConApp TyCon
fam_tc (HasCallStack => TCvSubst -> [Type] -> [Type]
TCvSubst -> [Type] -> [Type]
substTys TCvSubst
fam_subst [Type]
fam_tys)
  | Bool
otherwise
  = TyCon -> [Type] -> Type
mkTyConApp TyCon
tc [Type]
tys

-- | Get the type on the LHS of a coercion induced by a type/data
-- family instance.
coAxNthLHS :: CoAxiom br -> Int -> Type
coAxNthLHS :: CoAxiom br -> Int -> Type
coAxNthLHS CoAxiom br
ax Int
ind =
  TyCon -> [Type] -> Type
mkTyConApp (CoAxiom br -> TyCon
forall (br :: BranchFlag). CoAxiom br -> TyCon
coAxiomTyCon CoAxiom br
ax) (CoAxBranch -> [Type]
coAxBranchLHS (CoAxiom br -> Int -> CoAxBranch
forall (br :: BranchFlag). CoAxiom br -> Int -> CoAxBranch
coAxiomNthBranch CoAxiom br
ax Int
ind))

isFamFreeTy :: Type -> Bool
isFamFreeTy :: Type -> Bool
isFamFreeTy Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Bool
isFamFreeTy Type
ty'
isFamFreeTy (TyVarTy TyVar
_)       = Bool
True
isFamFreeTy (LitTy {})        = Bool
True
isFamFreeTy (TyConApp TyCon
tc [Type]
tys) = (Type -> Bool) -> [Type] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
all Type -> Bool
isFamFreeTy [Type]
tys Bool -> Bool -> Bool
&& TyCon -> Bool
isFamFreeTyCon TyCon
tc
isFamFreeTy (AppTy Type
a Type
b)       = Type -> Bool
isFamFreeTy Type
a Bool -> Bool -> Bool
&& Type -> Bool
isFamFreeTy Type
b
isFamFreeTy (FunTy AnonArgFlag
_ Type
a Type
b)     = Type -> Bool
isFamFreeTy Type
a Bool -> Bool -> Bool
&& Type -> Bool
isFamFreeTy Type
b
isFamFreeTy (ForAllTy VarBndr TyVar ArgFlag
_ Type
ty)   = Type -> Bool
isFamFreeTy Type
ty
isFamFreeTy (CastTy Type
ty KindCoercion
_)     = Type -> Bool
isFamFreeTy Type
ty
isFamFreeTy (CoercionTy KindCoercion
_)    = Bool
False  -- Not sure about this

-- | Does this type classify a core (unlifted) Coercion?
-- At either role nominal or representational
--    (t1 ~# t2) or (t1 ~R# t2)
-- See Note [Types for coercions, predicates, and evidence] in TyCoRep
isCoVarType :: Type -> Bool
  -- ToDo: should we check saturation?
isCoVarType :: Type -> Bool
isCoVarType Type
ty
  | Just TyCon
tc <- Type -> Maybe TyCon
tyConAppTyCon_maybe Type
ty
  = TyCon
tc TyCon -> Unique -> Bool
forall a. Uniquable a => a -> Unique -> Bool
`hasKey` Unique
eqPrimTyConKey Bool -> Bool -> Bool
|| TyCon
tc TyCon -> Unique -> Bool
forall a. Uniquable a => a -> Unique -> Bool
`hasKey` Unique
eqReprPrimTyConKey
  | Bool
otherwise
  = Bool
False


{-
************************************************************************
*                                                                      *
\subsection{Liftedness}
*                                                                      *
************************************************************************
-}

-- | Returns Just True if this type is surely lifted, Just False
-- if it is surely unlifted, Nothing if we can't be sure (i.e., it is
-- levity polymorphic), and panics if the kind does not have the shape
-- TYPE r.
isLiftedType_maybe :: HasDebugCallStack => Type -> Maybe Bool
isLiftedType_maybe :: Type -> Maybe Bool
isLiftedType_maybe Type
ty = Type -> Maybe Bool
go (HasDebugCallStack => Type -> Type
Type -> Type
getRuntimeRep Type
ty)
  where
    go :: Type -> Maybe Bool
go Type
rr | Just Type
rr' <- Type -> Maybe Type
coreView Type
rr = Type -> Maybe Bool
go Type
rr'
          | Type -> Bool
isLiftedRuntimeRep Type
rr  = Bool -> Maybe Bool
forall a. a -> Maybe a
Just Bool
True
          | TyConApp {} <- Type
rr      = Bool -> Maybe Bool
forall a. a -> Maybe a
Just Bool
False  -- Everything else is unlifted
          | Bool
otherwise              = Maybe Bool
forall a. Maybe a
Nothing     -- levity polymorphic

-- | See "Type#type_classification" for what an unlifted type is.
-- Panics on levity polymorphic types; See 'mightBeUnliftedType' for
-- a more approximate predicate that behaves better in the presence of
-- levity polymorphism.
isUnliftedType :: HasDebugCallStack => Type -> Bool
        -- isUnliftedType returns True for forall'd unlifted types:
        --      x :: forall a. Int#
        -- I found bindings like these were getting floated to the top level.
        -- They are pretty bogus types, mind you.  It would be better never to
        -- construct them
isUnliftedType :: Type -> Bool
isUnliftedType Type
ty
  = Bool -> Bool
not (HasDebugCallStack => Type -> Maybe Bool
Type -> Maybe Bool
isLiftedType_maybe Type
ty Maybe Bool -> Bool -> Bool
forall a. Maybe a -> a -> a
`orElse`
         String -> SDoc -> Bool
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"isUnliftedType" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
ty SDoc -> SDoc -> SDoc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr (HasDebugCallStack => Type -> Type
Type -> Type
typeKind Type
ty)))

-- | Returns:
--
-- * 'False' if the type is /guaranteed/ lifted or
-- * 'True' if it is unlifted, OR we aren't sure (e.g. in a levity-polymorphic case)
mightBeUnliftedType :: Type -> Bool
mightBeUnliftedType :: Type -> Bool
mightBeUnliftedType Type
ty
  = case HasDebugCallStack => Type -> Maybe Bool
Type -> Maybe Bool
isLiftedType_maybe Type
ty of
      Just Bool
is_lifted -> Bool -> Bool
not Bool
is_lifted
      Maybe Bool
Nothing -> Bool
True

-- | Is this a type of kind RuntimeRep? (e.g. LiftedRep)
isRuntimeRepKindedTy :: Type -> Bool
isRuntimeRepKindedTy :: Type -> Bool
isRuntimeRepKindedTy = Type -> Bool
isRuntimeRepTy (Type -> Bool) -> (Type -> Type) -> Type -> Bool
forall b c a. (b -> c) -> (a -> b) -> a -> c
. HasDebugCallStack => Type -> Type
Type -> Type
typeKind

-- | Drops prefix of RuntimeRep constructors in 'TyConApp's. Useful for e.g.
-- dropping 'LiftedRep arguments of unboxed tuple TyCon applications:
--
--   dropRuntimeRepArgs [ 'LiftedRep, 'IntRep
--                      , String, Int# ] == [String, Int#]
--
dropRuntimeRepArgs :: [Type] -> [Type]
dropRuntimeRepArgs :: [Type] -> [Type]
dropRuntimeRepArgs = (Type -> Bool) -> [Type] -> [Type]
forall a. (a -> Bool) -> [a] -> [a]
dropWhile Type -> Bool
isRuntimeRepKindedTy

-- | Extract the RuntimeRep classifier of a type. For instance,
-- @getRuntimeRep_maybe Int = LiftedRep@. Returns 'Nothing' if this is not
-- possible.
getRuntimeRep_maybe :: HasDebugCallStack
                    => Type -> Maybe Type
getRuntimeRep_maybe :: Type -> Maybe Type
getRuntimeRep_maybe = HasDebugCallStack => Type -> Maybe Type
Type -> Maybe Type
kindRep_maybe (Type -> Maybe Type) -> (Type -> Type) -> Type -> Maybe Type
forall b c a. (b -> c) -> (a -> b) -> a -> c
. HasDebugCallStack => Type -> Type
Type -> Type
typeKind

-- | Extract the RuntimeRep classifier of a type. For instance,
-- @getRuntimeRep_maybe Int = LiftedRep@. Panics if this is not possible.
getRuntimeRep :: HasDebugCallStack => Type -> Type
getRuntimeRep :: Type -> Type
getRuntimeRep Type
ty
  = case HasDebugCallStack => Type -> Maybe Type
Type -> Maybe Type
getRuntimeRep_maybe Type
ty of
      Just Type
r  -> Type
r
      Maybe Type
Nothing -> String -> SDoc -> Type
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"getRuntimeRep" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
ty SDoc -> SDoc -> SDoc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr (HasDebugCallStack => Type -> Type
Type -> Type
typeKind Type
ty))

isUnboxedTupleType :: Type -> Bool
isUnboxedTupleType :: Type -> Bool
isUnboxedTupleType Type
ty
  = Type -> TyCon
tyConAppTyCon (HasDebugCallStack => Type -> Type
Type -> Type
getRuntimeRep Type
ty) TyCon -> Unique -> Bool
forall a. Uniquable a => a -> Unique -> Bool
`hasKey` Unique
tupleRepDataConKey
  -- NB: Do not use typePrimRep, as that can't tell the difference between
  -- unboxed tuples and unboxed sums


isUnboxedSumType :: Type -> Bool
isUnboxedSumType :: Type -> Bool
isUnboxedSumType Type
ty
  = Type -> TyCon
tyConAppTyCon (HasDebugCallStack => Type -> Type
Type -> Type
getRuntimeRep Type
ty) TyCon -> Unique -> Bool
forall a. Uniquable a => a -> Unique -> Bool
`hasKey` Unique
sumRepDataConKey

-- | See "Type#type_classification" for what an algebraic type is.
-- Should only be applied to /types/, as opposed to e.g. partially
-- saturated type constructors
isAlgType :: Type -> Bool
isAlgType :: Type -> Bool
isAlgType Type
ty
  = case HasDebugCallStack => Type -> Maybe (TyCon, [Type])
Type -> Maybe (TyCon, [Type])
splitTyConApp_maybe Type
ty of
      Just (TyCon
tc, [Type]
ty_args) -> ASSERT( ty_args `lengthIs` tyConArity tc )
                            TyCon -> Bool
isAlgTyCon TyCon
tc
      Maybe (TyCon, [Type])
_other             -> Bool
False

-- | Check whether a type is a data family type
isDataFamilyAppType :: Type -> Bool
isDataFamilyAppType :: Type -> Bool
isDataFamilyAppType Type
ty = case Type -> Maybe TyCon
tyConAppTyCon_maybe Type
ty of
                           Just TyCon
tc -> TyCon -> Bool
isDataFamilyTyCon TyCon
tc
                           Maybe TyCon
_       -> Bool
False

-- | Computes whether an argument (or let right hand side) should
-- be computed strictly or lazily, based only on its type.
-- Currently, it's just 'isUnliftedType'. Panics on levity-polymorphic types.
isStrictType :: HasDebugCallStack => Type -> Bool
isStrictType :: Type -> Bool
isStrictType = HasDebugCallStack => Type -> Bool
Type -> Bool
isUnliftedType

isPrimitiveType :: Type -> Bool
-- ^ Returns true of types that are opaque to Haskell.
isPrimitiveType :: Type -> Bool
isPrimitiveType Type
ty = case HasDebugCallStack => Type -> Maybe (TyCon, [Type])
Type -> Maybe (TyCon, [Type])
splitTyConApp_maybe Type
ty of
                        Just (TyCon
tc, [Type]
ty_args) -> ASSERT( ty_args `lengthIs` tyConArity tc )
                                              TyCon -> Bool
isPrimTyCon TyCon
tc
                        Maybe (TyCon, [Type])
_                  -> Bool
False

{-
************************************************************************
*                                                                      *
\subsection{Join points}
*                                                                      *
************************************************************************
-}

-- | Determine whether a type could be the type of a join point of given total
-- arity, according to the polymorphism rule. A join point cannot be polymorphic
-- in its return type, since given
--   join j @a @b x y z = e1 in e2,
-- the types of e1 and e2 must be the same, and a and b are not in scope for e2.
-- (See Note [The polymorphism rule of join points] in CoreSyn.) Returns False
-- also if the type simply doesn't have enough arguments.
--
-- Note that we need to know how many arguments (type *and* value) the putative
-- join point takes; for instance, if
--   j :: forall a. a -> Int
-- then j could be a binary join point returning an Int, but it could *not* be a
-- unary join point returning a -> Int.
--
-- TODO: See Note [Excess polymorphism and join points]
isValidJoinPointType :: JoinArity -> Type -> Bool
isValidJoinPointType :: Int -> Type -> Bool
isValidJoinPointType Int
arity Type
ty
  = VarSet -> Int -> Type -> Bool
forall a. (Eq a, Num a) => VarSet -> a -> Type -> Bool
valid_under VarSet
emptyVarSet Int
arity Type
ty
  where
    valid_under :: VarSet -> a -> Type -> Bool
valid_under VarSet
tvs a
arity Type
ty
      | a
arity a -> a -> Bool
forall a. Eq a => a -> a -> Bool
== a
0
      = VarSet -> Bool
isEmptyVarSet (VarSet
tvs VarSet -> VarSet -> VarSet
`intersectVarSet` Type -> VarSet
tyCoVarsOfType Type
ty)
      | Just (TyVar
t, Type
ty') <- Type -> Maybe (TyVar, Type)
splitForAllTy_maybe Type
ty
      = VarSet -> a -> Type -> Bool
valid_under (VarSet
tvs VarSet -> TyVar -> VarSet
`extendVarSet` TyVar
t) (a
aritya -> a -> a
forall a. Num a => a -> a -> a
-a
1) Type
ty'
      | Just (Type
_, Type
res_ty) <- Type -> Maybe (Type, Type)
splitFunTy_maybe Type
ty
      = VarSet -> a -> Type -> Bool
valid_under VarSet
tvs (a
aritya -> a -> a
forall a. Num a => a -> a -> a
-a
1) Type
res_ty
      | Bool
otherwise
      = Bool
False

{- Note [Excess polymorphism and join points]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In principle, if a function would be a join point except that it fails
the polymorphism rule (see Note [The polymorphism rule of join points] in
CoreSyn), it can still be made a join point with some effort. This is because
all tail calls must return the same type (they return to the same context!), and
thus if the return type depends on an argument, that argument must always be the
same.

For instance, consider:

  let f :: forall a. a -> Char -> [a]
      f @a x c = ... f @a y 'a' ...
  in ... f @Int 1 'b' ... f @Int 2 'c' ...

(where the calls are tail calls). `f` fails the polymorphism rule because its
return type is [a], where [a] is bound. But since the type argument is always
'Int', we can rewrite it as:

  let f' :: Int -> Char -> [Int]
      f' x c = ... f' y 'a' ...
  in ... f' 1 'b' ... f 2 'c' ...

and now we can make f' a join point:

  join f' :: Int -> Char -> [Int]
       f' x c = ... jump f' y 'a' ...
  in ... jump f' 1 'b' ... jump f' 2 'c' ...

It's not clear that this comes up often, however. TODO: Measure how often and
add this analysis if necessary.  See #14620.


************************************************************************
*                                                                      *
\subsection{Sequencing on types}
*                                                                      *
************************************************************************
-}

seqType :: Type -> ()
seqType :: Type -> ()
seqType (LitTy TyLit
n)                   = TyLit
n TyLit -> () -> ()
`seq` ()
seqType (TyVarTy TyVar
tv)                = TyVar
tv TyVar -> () -> ()
`seq` ()
seqType (AppTy Type
t1 Type
t2)               = Type -> ()
seqType Type
t1 () -> () -> ()
`seq` Type -> ()
seqType Type
t2
seqType (FunTy AnonArgFlag
_ Type
t1 Type
t2)             = Type -> ()
seqType Type
t1 () -> () -> ()
`seq` Type -> ()
seqType Type
t2
seqType (TyConApp TyCon
tc [Type]
tys)           = TyCon
tc TyCon -> () -> ()
`seq` [Type] -> ()
seqTypes [Type]
tys
seqType (ForAllTy (Bndr TyVar
tv ArgFlag
_) Type
ty)   = Type -> ()
seqType (TyVar -> Type
varType TyVar
tv) () -> () -> ()
`seq` Type -> ()
seqType Type
ty
seqType (CastTy Type
ty KindCoercion
co)              = Type -> ()
seqType Type
ty () -> () -> ()
`seq` KindCoercion -> ()
seqCo KindCoercion
co
seqType (CoercionTy KindCoercion
co)             = KindCoercion -> ()
seqCo KindCoercion
co

seqTypes :: [Type] -> ()
seqTypes :: [Type] -> ()
seqTypes []       = ()
seqTypes (Type
ty:[Type]
tys) = Type -> ()
seqType Type
ty () -> () -> ()
`seq` [Type] -> ()
seqTypes [Type]
tys

{-
************************************************************************
*                                                                      *
                Comparison for types
        (We don't use instances so that we know where it happens)
*                                                                      *
************************************************************************

Note [Equality on AppTys]
~~~~~~~~~~~~~~~~~~~~~~~~~
In our cast-ignoring equality, we want to say that the following two
are equal:

  (Maybe |> co) (Int |> co')   ~?       Maybe Int

But the left is an AppTy while the right is a TyConApp. The solution is
to use repSplitAppTy_maybe to break up the TyConApp into its pieces and
then continue. Easy to do, but also easy to forget to do.

-}

eqType :: Type -> Type -> Bool
-- ^ Type equality on source types. Does not look through @newtypes@ or
-- 'PredType's, but it does look through type synonyms.
-- This first checks that the kinds of the types are equal and then
-- checks whether the types are equal, ignoring casts and coercions.
-- (The kind check is a recursive call, but since all kinds have type
-- @Type@, there is no need to check the types of kinds.)
-- See also Note [Non-trivial definitional equality] in TyCoRep.
eqType :: Type -> Type -> Bool
eqType Type
t1 Type
t2 = Ordering -> Bool
isEqual (Ordering -> Bool) -> Ordering -> Bool
forall a b. (a -> b) -> a -> b
$ Type -> Type -> Ordering
nonDetCmpType Type
t1 Type
t2
  -- It's OK to use nonDetCmpType here and eqType is deterministic,
  -- nonDetCmpType does equality deterministically

-- | Compare types with respect to a (presumably) non-empty 'RnEnv2'.
eqTypeX :: RnEnv2 -> Type -> Type -> Bool
eqTypeX :: RnEnv2 -> Type -> Type -> Bool
eqTypeX RnEnv2
env Type
t1 Type
t2 = Ordering -> Bool
isEqual (Ordering -> Bool) -> Ordering -> Bool
forall a b. (a -> b) -> a -> b
$ RnEnv2 -> Type -> Type -> Ordering
nonDetCmpTypeX RnEnv2
env Type
t1 Type
t2
  -- It's OK to use nonDetCmpType here and eqTypeX is deterministic,
  -- nonDetCmpTypeX does equality deterministically

-- | Type equality on lists of types, looking through type synonyms
-- but not newtypes.
eqTypes :: [Type] -> [Type] -> Bool
eqTypes :: [Type] -> [Type] -> Bool
eqTypes [Type]
tys1 [Type]
tys2 = Ordering -> Bool
isEqual (Ordering -> Bool) -> Ordering -> Bool
forall a b. (a -> b) -> a -> b
$ [Type] -> [Type] -> Ordering
nonDetCmpTypes [Type]
tys1 [Type]
tys2
  -- It's OK to use nonDetCmpType here and eqTypes is deterministic,
  -- nonDetCmpTypes does equality deterministically

eqVarBndrs :: RnEnv2 -> [Var] -> [Var] -> Maybe RnEnv2
-- Check that the var lists are the same length
-- and have matching kinds; if so, extend the RnEnv2
-- Returns Nothing if they don't match
eqVarBndrs :: RnEnv2 -> [TyVar] -> [TyVar] -> Maybe RnEnv2
eqVarBndrs RnEnv2
env [] []
 = RnEnv2 -> Maybe RnEnv2
forall a. a -> Maybe a
Just RnEnv2
env
eqVarBndrs RnEnv2
env (TyVar
tv1:[TyVar]
tvs1) (TyVar
tv2:[TyVar]
tvs2)
 | RnEnv2 -> Type -> Type -> Bool
eqTypeX RnEnv2
env (TyVar -> Type
varType TyVar
tv1) (TyVar -> Type
varType TyVar
tv2)
 = RnEnv2 -> [TyVar] -> [TyVar] -> Maybe RnEnv2
eqVarBndrs (RnEnv2 -> TyVar -> TyVar -> RnEnv2
rnBndr2 RnEnv2
env TyVar
tv1 TyVar
tv2) [TyVar]
tvs1 [TyVar]
tvs2
eqVarBndrs RnEnv2
_ [TyVar]
_ [TyVar]
_= Maybe RnEnv2
forall a. Maybe a
Nothing

-- Now here comes the real worker

{-
Note [nonDetCmpType nondeterminism]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
nonDetCmpType is implemented in terms of nonDetCmpTypeX. nonDetCmpTypeX
uses nonDetCmpTc which compares TyCons by their Unique value. Using Uniques for
ordering leads to nondeterminism. We hit the same problem in the TyVarTy case,
comparing type variables is nondeterministic, note the call to nonDetCmpVar in
nonDetCmpTypeX.
See Note [Unique Determinism] for more details.
-}

nonDetCmpType :: Type -> Type -> Ordering
nonDetCmpType :: Type -> Type -> Ordering
nonDetCmpType Type
t1 Type
t2
  -- we know k1 and k2 have the same kind, because they both have kind *.
  = RnEnv2 -> Type -> Type -> Ordering
nonDetCmpTypeX RnEnv2
rn_env Type
t1 Type
t2
  where
    rn_env :: RnEnv2
rn_env = InScopeSet -> RnEnv2
mkRnEnv2 (VarSet -> InScopeSet
mkInScopeSet ([Type] -> VarSet
tyCoVarsOfTypes [Type
t1, Type
t2]))

nonDetCmpTypes :: [Type] -> [Type] -> Ordering
nonDetCmpTypes :: [Type] -> [Type] -> Ordering
nonDetCmpTypes [Type]
ts1 [Type]
ts2 = RnEnv2 -> [Type] -> [Type] -> Ordering
nonDetCmpTypesX RnEnv2
rn_env [Type]
ts1 [Type]
ts2
  where
    rn_env :: RnEnv2
rn_env = InScopeSet -> RnEnv2
mkRnEnv2 (VarSet -> InScopeSet
mkInScopeSet ([Type] -> VarSet
tyCoVarsOfTypes ([Type]
ts1 [Type] -> [Type] -> [Type]
forall a. [a] -> [a] -> [a]
++ [Type]
ts2)))

-- | An ordering relation between two 'Type's (known below as @t1 :: k1@
-- and @t2 :: k2@)
data TypeOrdering = TLT  -- ^ @t1 < t2@
                  | TEQ  -- ^ @t1 ~ t2@ and there are no casts in either,
                         -- therefore we can conclude @k1 ~ k2@
                  | TEQX -- ^ @t1 ~ t2@ yet one of the types contains a cast so
                         -- they may differ in kind.
                  | TGT  -- ^ @t1 > t2@
                  deriving (TypeOrdering -> TypeOrdering -> Bool
(TypeOrdering -> TypeOrdering -> Bool)
-> (TypeOrdering -> TypeOrdering -> Bool) -> Eq TypeOrdering
forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
/= :: TypeOrdering -> TypeOrdering -> Bool
$c/= :: TypeOrdering -> TypeOrdering -> Bool
== :: TypeOrdering -> TypeOrdering -> Bool
$c== :: TypeOrdering -> TypeOrdering -> Bool
Eq, Eq TypeOrdering
Eq TypeOrdering
-> (TypeOrdering -> TypeOrdering -> Ordering)
-> (TypeOrdering -> TypeOrdering -> Bool)
-> (TypeOrdering -> TypeOrdering -> Bool)
-> (TypeOrdering -> TypeOrdering -> Bool)
-> (TypeOrdering -> TypeOrdering -> Bool)
-> (TypeOrdering -> TypeOrdering -> TypeOrdering)
-> (TypeOrdering -> TypeOrdering -> TypeOrdering)
-> Ord TypeOrdering
TypeOrdering -> TypeOrdering -> Bool
TypeOrdering -> TypeOrdering -> Ordering
TypeOrdering -> TypeOrdering -> TypeOrdering
forall a.
Eq a
-> (a -> a -> Ordering)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> Bool)
-> (a -> a -> a)
-> (a -> a -> a)
-> Ord a
min :: TypeOrdering -> TypeOrdering -> TypeOrdering
$cmin :: TypeOrdering -> TypeOrdering -> TypeOrdering
max :: TypeOrdering -> TypeOrdering -> TypeOrdering
$cmax :: TypeOrdering -> TypeOrdering -> TypeOrdering
>= :: TypeOrdering -> TypeOrdering -> Bool
$c>= :: TypeOrdering -> TypeOrdering -> Bool
> :: TypeOrdering -> TypeOrdering -> Bool
$c> :: TypeOrdering -> TypeOrdering -> Bool
<= :: TypeOrdering -> TypeOrdering -> Bool
$c<= :: TypeOrdering -> TypeOrdering -> Bool
< :: TypeOrdering -> TypeOrdering -> Bool
$c< :: TypeOrdering -> TypeOrdering -> Bool
compare :: TypeOrdering -> TypeOrdering -> Ordering
$ccompare :: TypeOrdering -> TypeOrdering -> Ordering
$cp1Ord :: Eq TypeOrdering
Ord, Int -> TypeOrdering
TypeOrdering -> Int
TypeOrdering -> [TypeOrdering]
TypeOrdering -> TypeOrdering
TypeOrdering -> TypeOrdering -> [TypeOrdering]
TypeOrdering -> TypeOrdering -> TypeOrdering -> [TypeOrdering]
(TypeOrdering -> TypeOrdering)
-> (TypeOrdering -> TypeOrdering)
-> (Int -> TypeOrdering)
-> (TypeOrdering -> Int)
-> (TypeOrdering -> [TypeOrdering])
-> (TypeOrdering -> TypeOrdering -> [TypeOrdering])
-> (TypeOrdering -> TypeOrdering -> [TypeOrdering])
-> (TypeOrdering -> TypeOrdering -> TypeOrdering -> [TypeOrdering])
-> Enum TypeOrdering
forall a.
(a -> a)
-> (a -> a)
-> (Int -> a)
-> (a -> Int)
-> (a -> [a])
-> (a -> a -> [a])
-> (a -> a -> [a])
-> (a -> a -> a -> [a])
-> Enum a
enumFromThenTo :: TypeOrdering -> TypeOrdering -> TypeOrdering -> [TypeOrdering]
$cenumFromThenTo :: TypeOrdering -> TypeOrdering -> TypeOrdering -> [TypeOrdering]
enumFromTo :: TypeOrdering -> TypeOrdering -> [TypeOrdering]
$cenumFromTo :: TypeOrdering -> TypeOrdering -> [TypeOrdering]
enumFromThen :: TypeOrdering -> TypeOrdering -> [TypeOrdering]
$cenumFromThen :: TypeOrdering -> TypeOrdering -> [TypeOrdering]
enumFrom :: TypeOrdering -> [TypeOrdering]
$cenumFrom :: TypeOrdering -> [TypeOrdering]
fromEnum :: TypeOrdering -> Int
$cfromEnum :: TypeOrdering -> Int
toEnum :: Int -> TypeOrdering
$ctoEnum :: Int -> TypeOrdering
pred :: TypeOrdering -> TypeOrdering
$cpred :: TypeOrdering -> TypeOrdering
succ :: TypeOrdering -> TypeOrdering
$csucc :: TypeOrdering -> TypeOrdering
Enum, TypeOrdering
TypeOrdering -> TypeOrdering -> Bounded TypeOrdering
forall a. a -> a -> Bounded a
maxBound :: TypeOrdering
$cmaxBound :: TypeOrdering
minBound :: TypeOrdering
$cminBound :: TypeOrdering
Bounded)

nonDetCmpTypeX :: RnEnv2 -> Type -> Type -> Ordering  -- Main workhorse
    -- See Note [Non-trivial definitional equality] in TyCoRep
nonDetCmpTypeX :: RnEnv2 -> Type -> Type -> Ordering
nonDetCmpTypeX RnEnv2
env Type
orig_t1 Type
orig_t2 =
    case RnEnv2 -> Type -> Type -> TypeOrdering
go RnEnv2
env Type
orig_t1 Type
orig_t2 of
      -- If there are casts then we also need to do a comparison of the kinds of
      -- the types being compared
      TypeOrdering
TEQX          -> TypeOrdering -> Ordering
toOrdering (TypeOrdering -> Ordering) -> TypeOrdering -> Ordering
forall a b. (a -> b) -> a -> b
$ RnEnv2 -> Type -> Type -> TypeOrdering
go RnEnv2
env Type
k1 Type
k2
      TypeOrdering
ty_ordering   -> TypeOrdering -> Ordering
toOrdering TypeOrdering
ty_ordering
  where
    k1 :: Type
k1 = HasDebugCallStack => Type -> Type
Type -> Type
typeKind Type
orig_t1
    k2 :: Type
k2 = HasDebugCallStack => Type -> Type
Type -> Type
typeKind Type
orig_t2

    toOrdering :: TypeOrdering -> Ordering
    toOrdering :: TypeOrdering -> Ordering
toOrdering TypeOrdering
TLT  = Ordering
LT
    toOrdering TypeOrdering
TEQ  = Ordering
EQ
    toOrdering TypeOrdering
TEQX = Ordering
EQ
    toOrdering TypeOrdering
TGT  = Ordering
GT

    liftOrdering :: Ordering -> TypeOrdering
    liftOrdering :: Ordering -> TypeOrdering
liftOrdering Ordering
LT = TypeOrdering
TLT
    liftOrdering Ordering
EQ = TypeOrdering
TEQ
    liftOrdering Ordering
GT = TypeOrdering
TGT

    thenCmpTy :: TypeOrdering -> TypeOrdering -> TypeOrdering
    thenCmpTy :: TypeOrdering -> TypeOrdering -> TypeOrdering
thenCmpTy TypeOrdering
TEQ  TypeOrdering
rel  = TypeOrdering
rel
    thenCmpTy TypeOrdering
TEQX TypeOrdering
rel  = TypeOrdering -> TypeOrdering
hasCast TypeOrdering
rel
    thenCmpTy TypeOrdering
rel  TypeOrdering
_    = TypeOrdering
rel

    hasCast :: TypeOrdering -> TypeOrdering
    hasCast :: TypeOrdering -> TypeOrdering
hasCast TypeOrdering
TEQ = TypeOrdering
TEQX
    hasCast TypeOrdering
rel = TypeOrdering
rel

    -- Returns both the resulting ordering relation between the two types
    -- and whether either contains a cast.
    go :: RnEnv2 -> Type -> Type -> TypeOrdering
    go :: RnEnv2 -> Type -> Type -> TypeOrdering
go RnEnv2
env Type
t1 Type
t2
      | Just Type
t1' <- Type -> Maybe Type
coreView Type
t1 = RnEnv2 -> Type -> Type -> TypeOrdering
go RnEnv2
env Type
t1' Type
t2
      | Just Type
t2' <- Type -> Maybe Type
coreView Type
t2 = RnEnv2 -> Type -> Type -> TypeOrdering
go RnEnv2
env Type
t1 Type
t2'

    go RnEnv2
env (TyVarTy TyVar
tv1)       (TyVarTy TyVar
tv2)
      = Ordering -> TypeOrdering
liftOrdering (Ordering -> TypeOrdering) -> Ordering -> TypeOrdering
forall a b. (a -> b) -> a -> b
$ RnEnv2 -> TyVar -> TyVar
rnOccL RnEnv2
env TyVar
tv1 TyVar -> TyVar -> Ordering
`nonDetCmpVar` RnEnv2 -> TyVar -> TyVar
rnOccR RnEnv2
env TyVar
tv2
    go RnEnv2
env (ForAllTy (Bndr TyVar
tv1 ArgFlag
_) Type
t1) (ForAllTy (Bndr TyVar
tv2 ArgFlag
_) Type
t2)
      = RnEnv2 -> Type -> Type -> TypeOrdering
go RnEnv2
env (TyVar -> Type
varType TyVar
tv1) (TyVar -> Type
varType TyVar
tv2)
        TypeOrdering -> TypeOrdering -> TypeOrdering
`thenCmpTy` RnEnv2 -> Type -> Type -> TypeOrdering
go (RnEnv2 -> TyVar -> TyVar -> RnEnv2
rnBndr2 RnEnv2
env TyVar
tv1 TyVar
tv2) Type
t1 Type
t2
        -- See Note [Equality on AppTys]
    go RnEnv2
env (AppTy Type
s1 Type
t1) Type
ty2
      | Just (Type
s2, Type
t2) <- HasDebugCallStack => Type -> Maybe (Type, Type)
Type -> Maybe (Type, Type)
repSplitAppTy_maybe Type
ty2
      = RnEnv2 -> Type -> Type -> TypeOrdering
go RnEnv2
env Type
s1 Type
s2 TypeOrdering -> TypeOrdering -> TypeOrdering
`thenCmpTy` RnEnv2 -> Type -> Type -> TypeOrdering
go RnEnv2
env Type
t1 Type
t2
    go RnEnv2
env Type
ty1 (AppTy Type
s2 Type
t2)
      | Just (Type
s1, Type
t1) <- HasDebugCallStack => Type -> Maybe (Type, Type)
Type -> Maybe (Type, Type)
repSplitAppTy_maybe Type
ty1
      = RnEnv2 -> Type -> Type -> TypeOrdering
go RnEnv2
env Type
s1 Type
s2 TypeOrdering -> TypeOrdering -> TypeOrdering
`thenCmpTy` RnEnv2 -> Type -> Type -> TypeOrdering
go RnEnv2
env Type
t1 Type
t2
    go RnEnv2
env (FunTy AnonArgFlag
_ Type
s1 Type
t1) (FunTy AnonArgFlag
_ Type
s2 Type
t2)
      = RnEnv2 -> Type -> Type -> TypeOrdering
go RnEnv2
env Type
s1 Type
s2 TypeOrdering -> TypeOrdering -> TypeOrdering
`thenCmpTy` RnEnv2 -> Type -> Type -> TypeOrdering
go RnEnv2
env Type
t1 Type
t2
    go RnEnv2
env (TyConApp TyCon
tc1 [Type]
tys1) (TyConApp TyCon
tc2 [Type]
tys2)
      = Ordering -> TypeOrdering
liftOrdering (TyCon
tc1 TyCon -> TyCon -> Ordering
`nonDetCmpTc` TyCon
tc2) TypeOrdering -> TypeOrdering -> TypeOrdering
`thenCmpTy` RnEnv2 -> [Type] -> [Type] -> TypeOrdering
gos RnEnv2
env [Type]
tys1 [Type]
tys2
    go RnEnv2
_   (LitTy TyLit
l1)          (LitTy TyLit
l2)          = Ordering -> TypeOrdering
liftOrdering (TyLit -> TyLit -> Ordering
forall a. Ord a => a -> a -> Ordering
compare TyLit
l1 TyLit
l2)
    go RnEnv2
env (CastTy Type
t1 KindCoercion
_)       Type
t2                  = TypeOrdering -> TypeOrdering
hasCast (TypeOrdering -> TypeOrdering) -> TypeOrdering -> TypeOrdering
forall a b. (a -> b) -> a -> b
$ RnEnv2 -> Type -> Type -> TypeOrdering
go RnEnv2
env Type
t1 Type
t2
    go RnEnv2
env Type
t1                  (CastTy Type
t2 KindCoercion
_)       = TypeOrdering -> TypeOrdering
hasCast (TypeOrdering -> TypeOrdering) -> TypeOrdering -> TypeOrdering
forall a b. (a -> b) -> a -> b
$ RnEnv2 -> Type -> Type -> TypeOrdering
go RnEnv2
env Type
t1 Type
t2

    go RnEnv2
_   (CoercionTy {})     (CoercionTy {})     = TypeOrdering
TEQ

        -- Deal with the rest: TyVarTy < CoercionTy < AppTy < LitTy < TyConApp < ForAllTy
    go RnEnv2
_ Type
ty1 Type
ty2
      = Ordering -> TypeOrdering
liftOrdering (Ordering -> TypeOrdering) -> Ordering -> TypeOrdering
forall a b. (a -> b) -> a -> b
$ (Type -> Int
get_rank Type
ty1) Int -> Int -> Ordering
forall a. Ord a => a -> a -> Ordering
`compare` (Type -> Int
get_rank Type
ty2)
      where get_rank :: Type -> Int
            get_rank :: Type -> Int
get_rank (CastTy {})
              = String -> SDoc -> Int
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"nonDetCmpTypeX.get_rank" ([Type] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Type
ty1,Type
ty2])
            get_rank (TyVarTy {})    = Int
0
            get_rank (CoercionTy {}) = Int
1
            get_rank (AppTy {})      = Int
3
            get_rank (LitTy {})      = Int
4
            get_rank (TyConApp {})   = Int
5
            get_rank (FunTy {})      = Int
6
            get_rank (ForAllTy {})   = Int
7

    gos :: RnEnv2 -> [Type] -> [Type] -> TypeOrdering
    gos :: RnEnv2 -> [Type] -> [Type] -> TypeOrdering
gos RnEnv2
_   []         []         = TypeOrdering
TEQ
    gos RnEnv2
_   []         [Type]
_          = TypeOrdering
TLT
    gos RnEnv2
_   [Type]
_          []         = TypeOrdering
TGT
    gos RnEnv2
env (Type
ty1:[Type]
tys1) (Type
ty2:[Type]
tys2) = RnEnv2 -> Type -> Type -> TypeOrdering
go RnEnv2
env Type
ty1 Type
ty2 TypeOrdering -> TypeOrdering -> TypeOrdering
`thenCmpTy` RnEnv2 -> [Type] -> [Type] -> TypeOrdering
gos RnEnv2
env [Type]
tys1 [Type]
tys2

-------------
nonDetCmpTypesX :: RnEnv2 -> [Type] -> [Type] -> Ordering
nonDetCmpTypesX :: RnEnv2 -> [Type] -> [Type] -> Ordering
nonDetCmpTypesX RnEnv2
_   []        []        = Ordering
EQ
nonDetCmpTypesX RnEnv2
env (Type
t1:[Type]
tys1) (Type
t2:[Type]
tys2) = RnEnv2 -> Type -> Type -> Ordering
nonDetCmpTypeX RnEnv2
env Type
t1 Type
t2
                                          Ordering -> Ordering -> Ordering
`thenCmp`
                                          RnEnv2 -> [Type] -> [Type] -> Ordering
nonDetCmpTypesX RnEnv2
env [Type]
tys1 [Type]
tys2
nonDetCmpTypesX RnEnv2
_   []        [Type]
_         = Ordering
LT
nonDetCmpTypesX RnEnv2
_   [Type]
_         []        = Ordering
GT

-------------
-- | Compare two 'TyCon's. NB: This should /never/ see 'Constraint' (as
-- recognized by Kind.isConstraintKindCon) which is considered a synonym for
-- 'Type' in Core.
-- See Note [Kind Constraint and kind Type] in Kind.
-- See Note [nonDetCmpType nondeterminism]
nonDetCmpTc :: TyCon -> TyCon -> Ordering
nonDetCmpTc :: TyCon -> TyCon -> Ordering
nonDetCmpTc TyCon
tc1 TyCon
tc2
  = ASSERT( not (isConstraintKindCon tc1) && not (isConstraintKindCon tc2) )
    Unique
u1 Unique -> Unique -> Ordering
`nonDetCmpUnique` Unique
u2
  where
    u1 :: Unique
u1  = TyCon -> Unique
tyConUnique TyCon
tc1
    u2 :: Unique
u2  = TyCon -> Unique
tyConUnique TyCon
tc2

{-
************************************************************************
*                                                                      *
        The kind of a type
*                                                                      *
************************************************************************

Note [typeKind vs tcTypeKind]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We have two functions to get the kind of a type

  * typeKind   ignores  the distinction between Constraint and *
  * tcTypeKind respects the distinction between Constraint and *

tcTypeKind is used by the type inference engine, for which Constraint
and * are different; after that we use typeKind.

See also Note [coreView vs tcView]

Note [Kinding rules for types]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In typeKind we consider Constraint and (TYPE LiftedRep) to be identical.
We then have

         t1 : TYPE rep1
         t2 : TYPE rep2
   (FUN) ----------------
         t1 -> t2 : Type

         ty : TYPE rep
         `a` is not free in rep
(FORALL) -----------------------
         forall a. ty : TYPE rep

In tcTypeKind we consider Constraint and (TYPE LiftedRep) to be distinct:

          t1 : TYPE rep1
          t2 : TYPE rep2
    (FUN) ----------------
          t1 -> t2 : Type

          t1 : Constraint
          t2 : TYPE rep
  (PRED1) ----------------
          t1 => t2 : Type

          t1 : Constraint
          t2 : Constraint
  (PRED2) ---------------------
          t1 => t2 : Constraint

          ty : TYPE rep
          `a` is not free in rep
(FORALL1) -----------------------
          forall a. ty : TYPE rep

          ty : Constraint
(FORALL2) -------------------------
          forall a. ty : Constraint

Note that:
* The only way we distinguish '->' from '=>' is by the fact
  that the argument is a PredTy.  Both are FunTys

Note [Phantom type variables in kinds]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider

  type K (r :: RuntimeRep) = Type   -- Note 'r' is unused
  data T r :: K r                   -- T :: forall r -> K r
  foo :: forall r. T r

The body of the forall in foo's type has kind (K r), and
normally it would make no sense to have
   forall r. (ty :: K r)
because the kind of the forall would escape the binding
of 'r'.  But in this case it's fine because (K r) exapands
to Type, so we expliclity /permit/ the type
   forall r. T r

To accommodate such a type, in typeKind (forall a.ty) we use
occCheckExpand to expand any type synonyms in the kind of 'ty'
to eliminate 'a'.  See kinding rule (FORALL) in
Note [Kinding rules for types]

And in TcValidity.checkEscapingKind, we use also use
occCheckExpand, for the same reason.
-}

-----------------------------
typeKind :: HasDebugCallStack => Type -> Kind
-- No need to expand synonyms
typeKind :: Type -> Type
typeKind (TyConApp TyCon
tc [Type]
tys) = HasDebugCallStack => Type -> [Type] -> Type
Type -> [Type] -> Type
piResultTys (TyCon -> Type
tyConKind TyCon
tc) [Type]
tys
typeKind (LitTy TyLit
l)         = TyLit -> Type
typeLiteralKind TyLit
l
typeKind (FunTy {})        = Type
liftedTypeKind
typeKind (TyVarTy TyVar
tyvar)   = TyVar -> Type
tyVarKind TyVar
tyvar
typeKind (CastTy Type
_ty KindCoercion
co)   = Pair Type -> Type
forall a. Pair a -> a
pSnd (Pair Type -> Type) -> Pair Type -> Type
forall a b. (a -> b) -> a -> b
$ KindCoercion -> Pair Type
coercionKind KindCoercion
co
typeKind (CoercionTy KindCoercion
co)   = KindCoercion -> Type
coercionType KindCoercion
co

typeKind (AppTy Type
fun Type
arg)
  = Type -> [Type] -> Type
go Type
fun [Type
arg]
  where
    -- Accumulate the type arugments, so we can call piResultTys,
    -- rather than a succession of calls to piResultTy (which is
    -- asymptotically costly as the number of arguments increases)
    go :: Type -> [Type] -> Type
go (AppTy Type
fun Type
arg) [Type]
args = Type -> [Type] -> Type
go Type
fun (Type
argType -> [Type] -> [Type]
forall a. a -> [a] -> [a]
:[Type]
args)
    go Type
fun             [Type]
args = HasDebugCallStack => Type -> [Type] -> Type
Type -> [Type] -> Type
piResultTys (HasDebugCallStack => Type -> Type
Type -> Type
typeKind Type
fun) [Type]
args

typeKind ty :: Type
ty@(ForAllTy {})
  = case [TyVar] -> Type -> Maybe Type
occCheckExpand [TyVar]
tvs Type
body_kind of
      -- We must make sure tv does not occur in kind
      -- As it is already out of scope!
      -- See Note [Phantom type variables in kinds]
      Just Type
k' -> Type
k'
      Maybe Type
Nothing -> String -> SDoc -> Type
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"typeKind"
                  (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
ty SDoc -> SDoc -> SDoc
$$ [TyVar] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyVar]
tvs SDoc -> SDoc -> SDoc
$$ Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
body SDoc -> SDoc -> SDoc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
body_kind)
  where
    ([TyVar]
tvs, Type
body) = Type -> ([TyVar], Type)
splitTyVarForAllTys Type
ty
    body_kind :: Type
body_kind   = HasDebugCallStack => Type -> Type
Type -> Type
typeKind Type
body

---------------------------------------------
-- Utilities to be used in Unify, which uses "tc" functions
---------------------------------------------

tcTypeKind :: HasDebugCallStack => Type -> Kind
-- No need to expand synonyms
tcTypeKind :: Type -> Type
tcTypeKind (TyConApp TyCon
tc [Type]
tys) = HasDebugCallStack => Type -> [Type] -> Type
Type -> [Type] -> Type
piResultTys (TyCon -> Type
tyConKind TyCon
tc) [Type]
tys
tcTypeKind (LitTy TyLit
l)         = TyLit -> Type
typeLiteralKind TyLit
l
tcTypeKind (TyVarTy TyVar
tyvar)   = TyVar -> Type
tyVarKind TyVar
tyvar
tcTypeKind (CastTy Type
_ty KindCoercion
co)   = Pair Type -> Type
forall a. Pair a -> a
pSnd (Pair Type -> Type) -> Pair Type -> Type
forall a b. (a -> b) -> a -> b
$ KindCoercion -> Pair Type
coercionKind KindCoercion
co
tcTypeKind (CoercionTy KindCoercion
co)   = KindCoercion -> Type
coercionType KindCoercion
co

tcTypeKind (FunTy { ft_af :: Type -> AnonArgFlag
ft_af = AnonArgFlag
af, ft_res :: Type -> Type
ft_res = Type
res })
  | AnonArgFlag
InvisArg <- AnonArgFlag
af
  , Type -> Bool
tcIsConstraintKind (HasDebugCallStack => Type -> Type
Type -> Type
tcTypeKind Type
res)
  = Type
constraintKind     -- Eq a => Ord a         :: Constraint
  | Bool
otherwise          -- Eq a => a -> a        :: TYPE LiftedRep
  = Type
liftedTypeKind     -- Eq a => Array# Int    :: Type LiftedRep (not TYPE PtrRep)

tcTypeKind (AppTy Type
fun Type
arg)
  = Type -> [Type] -> Type
go Type
fun [Type
arg]
  where
    -- Accumulate the type arugments, so we can call piResultTys,
    -- rather than a succession of calls to piResultTy (which is
    -- asymptotically costly as the number of arguments increases)
    go :: Type -> [Type] -> Type
go (AppTy Type
fun Type
arg) [Type]
args = Type -> [Type] -> Type
go Type
fun (Type
argType -> [Type] -> [Type]
forall a. a -> [a] -> [a]
:[Type]
args)
    go Type
fun             [Type]
args = HasDebugCallStack => Type -> [Type] -> Type
Type -> [Type] -> Type
piResultTys (HasDebugCallStack => Type -> Type
Type -> Type
tcTypeKind Type
fun) [Type]
args

tcTypeKind ty :: Type
ty@(ForAllTy {})
  | Type -> Bool
tcIsConstraintKind Type
body_kind
  = Type
constraintKind

  | Bool
otherwise
  = case [TyVar] -> Type -> Maybe Type
occCheckExpand [TyVar]
tvs Type
body_kind of
      -- We must make sure tv does not occur in kind
      -- As it is already out of scope!
      -- See Note [Phantom type variables in kinds]
      Just Type
k' -> Type
k'
      Maybe Type
Nothing -> String -> SDoc -> Type
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"tcTypeKind"
                  (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
ty SDoc -> SDoc -> SDoc
$$ [TyVar] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [TyVar]
tvs SDoc -> SDoc -> SDoc
$$ Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
body SDoc -> SDoc -> SDoc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
body_kind)
  where
    ([TyVar]
tvs, Type
body) = Type -> ([TyVar], Type)
splitTyVarForAllTys Type
ty
    body_kind :: Type
body_kind = HasDebugCallStack => Type -> Type
Type -> Type
tcTypeKind Type
body


isPredTy :: HasDebugCallStack => Type -> Bool
-- See Note [Types for coercions, predicates, and evidence] in TyCoRep
isPredTy :: Type -> Bool
isPredTy Type
ty = Type -> Bool
tcIsConstraintKind (HasDebugCallStack => Type -> Type
Type -> Type
tcTypeKind Type
ty)

-- tcIsConstraintKind stuff only makes sense in the typechecker
-- After that Constraint = Type
-- See Note [coreView vs tcView]
-- Defined here because it is used in isPredTy and tcRepSplitAppTy_maybe (sigh)
tcIsConstraintKind :: Kind -> Bool
tcIsConstraintKind :: Type -> Bool
tcIsConstraintKind Type
ty
  | Just (TyCon
tc, [Type]
args) <- HasCallStack => Type -> Maybe (TyCon, [Type])
Type -> Maybe (TyCon, [Type])
tcSplitTyConApp_maybe Type
ty    -- Note: tcSplit here
  , TyCon -> Bool
isConstraintKindCon TyCon
tc
  = ASSERT2( null args, ppr ty ) True

  | Bool
otherwise
  = Bool
False

-- | Is this kind equivalent to @*@?
--
-- This considers 'Constraint' to be distinct from @*@. For a version that
-- treats them as the same type, see 'isLiftedTypeKind'.
tcIsLiftedTypeKind :: Kind -> Bool
tcIsLiftedTypeKind :: Type -> Bool
tcIsLiftedTypeKind Type
ty
  | Just (TyCon
tc, [Type
arg]) <- HasCallStack => Type -> Maybe (TyCon, [Type])
Type -> Maybe (TyCon, [Type])
tcSplitTyConApp_maybe Type
ty    -- Note: tcSplit here
  , TyCon
tc TyCon -> Unique -> Bool
forall a. Uniquable a => a -> Unique -> Bool
`hasKey` Unique
tYPETyConKey
  = Type -> Bool
isLiftedRuntimeRep Type
arg
  | Bool
otherwise
  = Bool
False

-- | Is this kind equivalent to @TYPE r@ (for some unknown r)?
--
-- This considers 'Constraint' to be distinct from @*@.
tcIsRuntimeTypeKind :: Kind -> Bool
tcIsRuntimeTypeKind :: Type -> Bool
tcIsRuntimeTypeKind Type
ty
  | Just (TyCon
tc, [Type]
_) <- HasCallStack => Type -> Maybe (TyCon, [Type])
Type -> Maybe (TyCon, [Type])
tcSplitTyConApp_maybe Type
ty    -- Note: tcSplit here
  , TyCon
tc TyCon -> Unique -> Bool
forall a. Uniquable a => a -> Unique -> Bool
`hasKey` Unique
tYPETyConKey
  = Bool
True
  | Bool
otherwise
  = Bool
False

tcReturnsConstraintKind :: Kind -> Bool
-- True <=> the Kind ultimately returns a Constraint
--   E.g.  * -> Constraint
--         forall k. k -> Constraint
tcReturnsConstraintKind :: Type -> Bool
tcReturnsConstraintKind Type
kind
  | Just Type
kind' <- Type -> Maybe Type
tcView Type
kind = Type -> Bool
tcReturnsConstraintKind Type
kind'
tcReturnsConstraintKind (ForAllTy VarBndr TyVar ArgFlag
_ Type
ty)         = Type -> Bool
tcReturnsConstraintKind Type
ty
tcReturnsConstraintKind (FunTy { ft_res :: Type -> Type
ft_res = Type
ty }) = Type -> Bool
tcReturnsConstraintKind Type
ty
tcReturnsConstraintKind (TyConApp TyCon
tc [Type]
_)         = TyCon -> Bool
isConstraintKindCon TyCon
tc
tcReturnsConstraintKind Type
_                       = Bool
False

--------------------------
typeLiteralKind :: TyLit -> Kind
typeLiteralKind :: TyLit -> Type
typeLiteralKind (NumTyLit {}) = Type
typeNatKind
typeLiteralKind (StrTyLit {}) = Type
typeSymbolKind

-- | Returns True if a type is levity polymorphic. Should be the same
-- as (isKindLevPoly . typeKind) but much faster.
-- Precondition: The type has kind (TYPE blah)
isTypeLevPoly :: Type -> Bool
isTypeLevPoly :: Type -> Bool
isTypeLevPoly = Type -> Bool
go
  where
    go :: Type -> Bool
go ty :: Type
ty@(TyVarTy {})                           = Type -> Bool
check_kind Type
ty
    go ty :: Type
ty@(AppTy {})                             = Type -> Bool
check_kind Type
ty
    go ty :: Type
ty@(TyConApp TyCon
tc [Type]
_) | Bool -> Bool
not (TyCon -> Bool
isTcLevPoly TyCon
tc) = Bool
False
                          | Bool
otherwise            = Type -> Bool
check_kind Type
ty
    go (ForAllTy VarBndr TyVar ArgFlag
_ Type
ty)                           = Type -> Bool
go Type
ty
    go (FunTy {})                                = Bool
False
    go (LitTy {})                                = Bool
False
    go ty :: Type
ty@(CastTy {})                            = Type -> Bool
check_kind Type
ty
    go ty :: Type
ty@(CoercionTy {})                        = String -> SDoc -> Bool
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"isTypeLevPoly co" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
ty)

    check_kind :: Type -> Bool
check_kind = Type -> Bool
isKindLevPoly (Type -> Bool) -> (Type -> Type) -> Type -> Bool
forall b c a. (b -> c) -> (a -> b) -> a -> c
. HasDebugCallStack => Type -> Type
Type -> Type
typeKind

-- | Looking past all pi-types, is the end result potentially levity polymorphic?
-- Example: True for (forall r (a :: TYPE r). String -> a)
-- Example: False for (forall r1 r2 (a :: TYPE r1) (b :: TYPE r2). a -> b -> Type)
resultIsLevPoly :: Type -> Bool
resultIsLevPoly :: Type -> Bool
resultIsLevPoly = Type -> Bool
isTypeLevPoly (Type -> Bool) -> (Type -> Type) -> Type -> Bool
forall b c a. (b -> c) -> (a -> b) -> a -> c
. ([TyCoBinder], Type) -> Type
forall a b. (a, b) -> b
snd (([TyCoBinder], Type) -> Type)
-> (Type -> ([TyCoBinder], Type)) -> Type -> Type
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Type -> ([TyCoBinder], Type)
splitPiTys


{- **********************************************************************
*                                                                       *
           Occurs check expansion
%*                                                                      *
%********************************************************************* -}

{- Note [Occurs check expansion]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
(occurCheckExpand tv xi) expands synonyms in xi just enough to get rid
of occurrences of tv outside type function arguments, if that is
possible; otherwise, it returns Nothing.

For example, suppose we have
  type F a b = [a]
Then
  occCheckExpand b (F Int b) = Just [Int]
but
  occCheckExpand a (F a Int) = Nothing

We don't promise to do the absolute minimum amount of expanding
necessary, but we try not to do expansions we don't need to.  We
prefer doing inner expansions first.  For example,
  type F a b = (a, Int, a, [a])
  type G b   = Char
We have
  occCheckExpand b (F (G b)) = Just (F Char)
even though we could also expand F to get rid of b.
-}

occCheckExpand :: [Var] -> Type -> Maybe Type
-- See Note [Occurs check expansion]
-- We may have needed to do some type synonym unfolding in order to
-- get rid of the variable (or forall), so we also return the unfolded
-- version of the type, which is guaranteed to be syntactically free
-- of the given type variable.  If the type is already syntactically
-- free of the variable, then the same type is returned.
occCheckExpand :: [TyVar] -> Type -> Maybe Type
occCheckExpand [TyVar]
vs_to_avoid Type
ty
  | [TyVar] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [TyVar]
vs_to_avoid  -- Efficient shortcut
  = Type -> Maybe Type
forall a. a -> Maybe a
Just Type
ty           -- Can happen, eg. CoreUtils.mkSingleAltCase

  | Bool
otherwise
  = (VarSet, VarEnv TyVar) -> Type -> Maybe Type
go ([TyVar] -> VarSet
mkVarSet [TyVar]
vs_to_avoid, VarEnv TyVar
forall a. VarEnv a
emptyVarEnv) Type
ty
  where
    go :: (VarSet, VarEnv TyCoVar) -> Type -> Maybe Type
          -- The VarSet is the set of variables we are trying to avoid
          -- The VarEnv carries mappings necessary
          -- because of kind expansion
    go :: (VarSet, VarEnv TyVar) -> Type -> Maybe Type
go cxt :: (VarSet, VarEnv TyVar)
cxt@(VarSet
as, VarEnv TyVar
env) (TyVarTy TyVar
tv')
      | TyVar
tv' TyVar -> VarSet -> Bool
`elemVarSet` VarSet
as               = Maybe Type
forall a. Maybe a
Nothing
      | Just TyVar
tv'' <- VarEnv TyVar -> TyVar -> Maybe TyVar
forall a. VarEnv a -> TyVar -> Maybe a
lookupVarEnv VarEnv TyVar
env TyVar
tv' = Type -> Maybe Type
forall (m :: * -> *) a. Monad m => a -> m a
return (TyVar -> Type
mkTyVarTy TyVar
tv'')
      | Bool
otherwise                         = do { TyVar
tv'' <- (VarSet, VarEnv TyVar) -> TyVar -> Maybe TyVar
go_var (VarSet, VarEnv TyVar)
cxt TyVar
tv'
                                               ; Type -> Maybe Type
forall (m :: * -> *) a. Monad m => a -> m a
return (TyVar -> Type
mkTyVarTy TyVar
tv'') }

    go (VarSet, VarEnv TyVar)
_   ty :: Type
ty@(LitTy {}) = Type -> Maybe Type
forall (m :: * -> *) a. Monad m => a -> m a
return Type
ty
    go (VarSet, VarEnv TyVar)
cxt (AppTy Type
ty1 Type
ty2) = do { Type
ty1' <- (VarSet, VarEnv TyVar) -> Type -> Maybe Type
go (VarSet, VarEnv TyVar)
cxt Type
ty1
                                ; Type
ty2' <- (VarSet, VarEnv TyVar) -> Type -> Maybe Type
go (VarSet, VarEnv TyVar)
cxt Type
ty2
                                ; Type -> Maybe Type
forall (m :: * -> *) a. Monad m => a -> m a
return (Type -> Type -> Type
mkAppTy Type
ty1' Type
ty2') }
    go (VarSet, VarEnv TyVar)
cxt ty :: Type
ty@(FunTy AnonArgFlag
_ Type
ty1 Type
ty2)
       = do { Type
ty1' <- (VarSet, VarEnv TyVar) -> Type -> Maybe Type
go (VarSet, VarEnv TyVar)
cxt Type
ty1
            ; Type
ty2' <- (VarSet, VarEnv TyVar) -> Type -> Maybe Type
go (VarSet, VarEnv TyVar)
cxt Type
ty2
            ; Type -> Maybe Type
forall (m :: * -> *) a. Monad m => a -> m a
return (Type
ty { ft_arg :: Type
ft_arg = Type
ty1', ft_res :: Type
ft_res = Type
ty2' }) }
    go cxt :: (VarSet, VarEnv TyVar)
cxt@(VarSet
as, VarEnv TyVar
env) (ForAllTy (Bndr TyVar
tv ArgFlag
vis) Type
body_ty)
       = do { Type
ki' <- (VarSet, VarEnv TyVar) -> Type -> Maybe Type
go (VarSet, VarEnv TyVar)
cxt (TyVar -> Type
varType TyVar
tv)
            ; let tv' :: TyVar
tv' = TyVar -> Type -> TyVar
setVarType TyVar
tv Type
ki'
                  env' :: VarEnv TyVar
env' = VarEnv TyVar -> TyVar -> TyVar -> VarEnv TyVar
forall a. VarEnv a -> TyVar -> a -> VarEnv a
extendVarEnv VarEnv TyVar
env TyVar
tv TyVar
tv'
                  as' :: VarSet
as'  = VarSet
as VarSet -> TyVar -> VarSet
`delVarSet` TyVar
tv
            ; Type
body' <- (VarSet, VarEnv TyVar) -> Type -> Maybe Type
go (VarSet
as', VarEnv TyVar
env') Type
body_ty
            ; Type -> Maybe Type
forall (m :: * -> *) a. Monad m => a -> m a
return (VarBndr TyVar ArgFlag -> Type -> Type
ForAllTy (TyVar -> ArgFlag -> VarBndr TyVar ArgFlag
forall var argf. var -> argf -> VarBndr var argf
Bndr TyVar
tv' ArgFlag
vis) Type
body') }

    -- For a type constructor application, first try expanding away the
    -- offending variable from the arguments.  If that doesn't work, next
    -- see if the type constructor is a type synonym, and if so, expand
    -- it and try again.
    go (VarSet, VarEnv TyVar)
cxt ty :: Type
ty@(TyConApp TyCon
tc [Type]
tys)
      = case (Type -> Maybe Type) -> [Type] -> Maybe [Type]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM ((VarSet, VarEnv TyVar) -> Type -> Maybe Type
go (VarSet, VarEnv TyVar)
cxt) [Type]
tys of
          Just [Type]
tys' -> Type -> Maybe Type
forall (m :: * -> *) a. Monad m => a -> m a
return (TyCon -> [Type] -> Type
mkTyConApp TyCon
tc [Type]
tys')
          Maybe [Type]
Nothing | Just Type
ty' <- Type -> Maybe Type
tcView Type
ty -> (VarSet, VarEnv TyVar) -> Type -> Maybe Type
go (VarSet, VarEnv TyVar)
cxt Type
ty'
                  | Bool
otherwise             -> Maybe Type
forall a. Maybe a
Nothing
                      -- Failing that, try to expand a synonym

    go (VarSet, VarEnv TyVar)
cxt (CastTy Type
ty KindCoercion
co) =  do { Type
ty' <- (VarSet, VarEnv TyVar) -> Type -> Maybe Type
go (VarSet, VarEnv TyVar)
cxt Type
ty
                                ; KindCoercion
co' <- (VarSet, VarEnv TyVar) -> KindCoercion -> Maybe KindCoercion
go_co (VarSet, VarEnv TyVar)
cxt KindCoercion
co
                                ; Type -> Maybe Type
forall (m :: * -> *) a. Monad m => a -> m a
return (Type -> KindCoercion -> Type
mkCastTy Type
ty' KindCoercion
co') }
    go (VarSet, VarEnv TyVar)
cxt (CoercionTy KindCoercion
co) = do { KindCoercion
co' <- (VarSet, VarEnv TyVar) -> KindCoercion -> Maybe KindCoercion
go_co (VarSet, VarEnv TyVar)
cxt KindCoercion
co
                                ; Type -> Maybe Type
forall (m :: * -> *) a. Monad m => a -> m a
return (KindCoercion -> Type
mkCoercionTy KindCoercion
co') }

    ------------------
    go_var :: (VarSet, VarEnv TyVar) -> TyVar -> Maybe TyVar
go_var (VarSet, VarEnv TyVar)
cxt TyVar
v = do { Type
k' <- (VarSet, VarEnv TyVar) -> Type -> Maybe Type
go (VarSet, VarEnv TyVar)
cxt (TyVar -> Type
varType TyVar
v)
                      ; TyVar -> Maybe TyVar
forall (m :: * -> *) a. Monad m => a -> m a
return (TyVar -> Type -> TyVar
setVarType TyVar
v Type
k') }
           -- Works for TyVar and CoVar
           -- See Note [Occurrence checking: look inside kinds]

    ------------------
    go_mco :: (VarSet, VarEnv TyVar) -> MCoercionN -> Maybe MCoercionN
go_mco (VarSet, VarEnv TyVar)
_   MCoercionN
MRefl = MCoercionN -> Maybe MCoercionN
forall (m :: * -> *) a. Monad m => a -> m a
return MCoercionN
MRefl
    go_mco (VarSet, VarEnv TyVar)
ctx (MCo KindCoercion
co) = KindCoercion -> MCoercionN
MCo (KindCoercion -> MCoercionN)
-> Maybe KindCoercion -> Maybe MCoercionN
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> (VarSet, VarEnv TyVar) -> KindCoercion -> Maybe KindCoercion
go_co (VarSet, VarEnv TyVar)
ctx KindCoercion
co

    ------------------
    go_co :: (VarSet, VarEnv TyVar) -> KindCoercion -> Maybe KindCoercion
go_co (VarSet, VarEnv TyVar)
cxt (Refl Type
ty)                 = do { Type
ty' <- (VarSet, VarEnv TyVar) -> Type -> Maybe Type
go (VarSet, VarEnv TyVar)
cxt Type
ty
                                             ; KindCoercion -> Maybe KindCoercion
forall (m :: * -> *) a. Monad m => a -> m a
return (Type -> KindCoercion
mkNomReflCo Type
ty') }
    go_co (VarSet, VarEnv TyVar)
cxt (GRefl Role
r Type
ty MCoercionN
mco)          = do { MCoercionN
mco' <- (VarSet, VarEnv TyVar) -> MCoercionN -> Maybe MCoercionN
go_mco (VarSet, VarEnv TyVar)
cxt MCoercionN
mco
                                             ; Type
ty' <- (VarSet, VarEnv TyVar) -> Type -> Maybe Type
go (VarSet, VarEnv TyVar)
cxt Type
ty
                                             ; KindCoercion -> Maybe KindCoercion
forall (m :: * -> *) a. Monad m => a -> m a
return (Role -> Type -> MCoercionN -> KindCoercion
mkGReflCo Role
r Type
ty' MCoercionN
mco') }
      -- Note: Coercions do not contain type synonyms
    go_co (VarSet, VarEnv TyVar)
cxt (TyConAppCo Role
r TyCon
tc [KindCoercion]
args)    = do { [KindCoercion]
args' <- (KindCoercion -> Maybe KindCoercion)
-> [KindCoercion] -> Maybe [KindCoercion]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM ((VarSet, VarEnv TyVar) -> KindCoercion -> Maybe KindCoercion
go_co (VarSet, VarEnv TyVar)
cxt) [KindCoercion]
args
                                             ; KindCoercion -> Maybe KindCoercion
forall (m :: * -> *) a. Monad m => a -> m a
return (HasDebugCallStack =>
Role -> TyCon -> [KindCoercion] -> KindCoercion
Role -> TyCon -> [KindCoercion] -> KindCoercion
mkTyConAppCo Role
r TyCon
tc [KindCoercion]
args') }
    go_co (VarSet, VarEnv TyVar)
cxt (AppCo KindCoercion
co KindCoercion
arg)            = do { KindCoercion
co' <- (VarSet, VarEnv TyVar) -> KindCoercion -> Maybe KindCoercion
go_co (VarSet, VarEnv TyVar)
cxt KindCoercion
co
                                             ; KindCoercion
arg' <- (VarSet, VarEnv TyVar) -> KindCoercion -> Maybe KindCoercion
go_co (VarSet, VarEnv TyVar)
cxt KindCoercion
arg
                                             ; KindCoercion -> Maybe KindCoercion
forall (m :: * -> *) a. Monad m => a -> m a
return (KindCoercion -> KindCoercion -> KindCoercion
mkAppCo KindCoercion
co' KindCoercion
arg') }
    go_co cxt :: (VarSet, VarEnv TyVar)
cxt@(VarSet
as, VarEnv TyVar
env) (ForAllCo TyVar
tv KindCoercion
kind_co KindCoercion
body_co)
      = do { KindCoercion
kind_co' <- (VarSet, VarEnv TyVar) -> KindCoercion -> Maybe KindCoercion
go_co (VarSet, VarEnv TyVar)
cxt KindCoercion
kind_co
           ; let tv' :: TyVar
tv' = TyVar -> Type -> TyVar
setVarType TyVar
tv (Type -> TyVar) -> Type -> TyVar
forall a b. (a -> b) -> a -> b
$
                       Pair Type -> Type
forall a. Pair a -> a
pFst (KindCoercion -> Pair Type
coercionKind KindCoercion
kind_co')
                 env' :: VarEnv TyVar
env' = VarEnv TyVar -> TyVar -> TyVar -> VarEnv TyVar
forall a. VarEnv a -> TyVar -> a -> VarEnv a
extendVarEnv VarEnv TyVar
env TyVar
tv TyVar
tv'
                 as' :: VarSet
as'  = VarSet
as VarSet -> TyVar -> VarSet
`delVarSet` TyVar
tv
           ; KindCoercion
body' <- (VarSet, VarEnv TyVar) -> KindCoercion -> Maybe KindCoercion
go_co (VarSet
as', VarEnv TyVar
env') KindCoercion
body_co
           ; KindCoercion -> Maybe KindCoercion
forall (m :: * -> *) a. Monad m => a -> m a
return (TyVar -> KindCoercion -> KindCoercion -> KindCoercion
ForAllCo TyVar
tv' KindCoercion
kind_co' KindCoercion
body') }
    go_co (VarSet, VarEnv TyVar)
cxt (FunCo Role
r KindCoercion
co1 KindCoercion
co2)         = do { KindCoercion
co1' <- (VarSet, VarEnv TyVar) -> KindCoercion -> Maybe KindCoercion
go_co (VarSet, VarEnv TyVar)
cxt KindCoercion
co1
                                             ; KindCoercion
co2' <- (VarSet, VarEnv TyVar) -> KindCoercion -> Maybe KindCoercion
go_co (VarSet, VarEnv TyVar)
cxt KindCoercion
co2
                                             ; KindCoercion -> Maybe KindCoercion
forall (m :: * -> *) a. Monad m => a -> m a
return (Role -> KindCoercion -> KindCoercion -> KindCoercion
mkFunCo Role
r KindCoercion
co1' KindCoercion
co2') }
    go_co cxt :: (VarSet, VarEnv TyVar)
cxt@(VarSet
as,VarEnv TyVar
env) (CoVarCo TyVar
c)
      | TyVar
c TyVar -> VarSet -> Bool
`elemVarSet` VarSet
as               = Maybe KindCoercion
forall a. Maybe a
Nothing
      | Just TyVar
c' <- VarEnv TyVar -> TyVar -> Maybe TyVar
forall a. VarEnv a -> TyVar -> Maybe a
lookupVarEnv VarEnv TyVar
env TyVar
c   = KindCoercion -> Maybe KindCoercion
forall (m :: * -> *) a. Monad m => a -> m a
return (TyVar -> KindCoercion
mkCoVarCo TyVar
c')
      | Bool
otherwise                       = do { TyVar
c' <- (VarSet, VarEnv TyVar) -> TyVar -> Maybe TyVar
go_var (VarSet, VarEnv TyVar)
cxt TyVar
c
                                             ; KindCoercion -> Maybe KindCoercion
forall (m :: * -> *) a. Monad m => a -> m a
return (TyVar -> KindCoercion
mkCoVarCo TyVar
c') }
    go_co (VarSet, VarEnv TyVar)
cxt (HoleCo CoercionHole
h)                = do { TyVar
c' <- (VarSet, VarEnv TyVar) -> TyVar -> Maybe TyVar
go_var (VarSet, VarEnv TyVar)
cxt (CoercionHole -> TyVar
ch_co_var CoercionHole
h)
                                             ; KindCoercion -> Maybe KindCoercion
forall (m :: * -> *) a. Monad m => a -> m a
return (CoercionHole -> KindCoercion
HoleCo (CoercionHole
h { ch_co_var :: TyVar
ch_co_var = TyVar
c' })) }
    go_co (VarSet, VarEnv TyVar)
cxt (AxiomInstCo CoAxiom Branched
ax Int
ind [KindCoercion]
args) = do { [KindCoercion]
args' <- (KindCoercion -> Maybe KindCoercion)
-> [KindCoercion] -> Maybe [KindCoercion]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM ((VarSet, VarEnv TyVar) -> KindCoercion -> Maybe KindCoercion
go_co (VarSet, VarEnv TyVar)
cxt) [KindCoercion]
args
                                             ; KindCoercion -> Maybe KindCoercion
forall (m :: * -> *) a. Monad m => a -> m a
return (CoAxiom Branched -> Int -> [KindCoercion] -> KindCoercion
mkAxiomInstCo CoAxiom Branched
ax Int
ind [KindCoercion]
args') }
    go_co (VarSet, VarEnv TyVar)
cxt (UnivCo UnivCoProvenance
p Role
r Type
ty1 Type
ty2)      = do { UnivCoProvenance
p' <- (VarSet, VarEnv TyVar)
-> UnivCoProvenance -> Maybe UnivCoProvenance
go_prov (VarSet, VarEnv TyVar)
cxt UnivCoProvenance
p
                                             ; Type
ty1' <- (VarSet, VarEnv TyVar) -> Type -> Maybe Type
go (VarSet, VarEnv TyVar)
cxt Type
ty1
                                             ; Type
ty2' <- (VarSet, VarEnv TyVar) -> Type -> Maybe Type
go (VarSet, VarEnv TyVar)
cxt Type
ty2
                                             ; KindCoercion -> Maybe KindCoercion
forall (m :: * -> *) a. Monad m => a -> m a
return (UnivCoProvenance -> Role -> Type -> Type -> KindCoercion
mkUnivCo UnivCoProvenance
p' Role
r Type
ty1' Type
ty2') }
    go_co (VarSet, VarEnv TyVar)
cxt (SymCo KindCoercion
co)                = do { KindCoercion
co' <- (VarSet, VarEnv TyVar) -> KindCoercion -> Maybe KindCoercion
go_co (VarSet, VarEnv TyVar)
cxt KindCoercion
co
                                             ; KindCoercion -> Maybe KindCoercion
forall (m :: * -> *) a. Monad m => a -> m a
return (KindCoercion -> KindCoercion
mkSymCo KindCoercion
co') }
    go_co (VarSet, VarEnv TyVar)
cxt (TransCo KindCoercion
co1 KindCoercion
co2)         = do { KindCoercion
co1' <- (VarSet, VarEnv TyVar) -> KindCoercion -> Maybe KindCoercion
go_co (VarSet, VarEnv TyVar)
cxt KindCoercion
co1
                                             ; KindCoercion
co2' <- (VarSet, VarEnv TyVar) -> KindCoercion -> Maybe KindCoercion
go_co (VarSet, VarEnv TyVar)
cxt KindCoercion
co2
                                             ; KindCoercion -> Maybe KindCoercion
forall (m :: * -> *) a. Monad m => a -> m a
return (KindCoercion -> KindCoercion -> KindCoercion
mkTransCo KindCoercion
co1' KindCoercion
co2') }
    go_co (VarSet, VarEnv TyVar)
cxt (NthCo Role
r Int
n KindCoercion
co)            = do { KindCoercion
co' <- (VarSet, VarEnv TyVar) -> KindCoercion -> Maybe KindCoercion
go_co (VarSet, VarEnv TyVar)
cxt KindCoercion
co
                                             ; KindCoercion -> Maybe KindCoercion
forall (m :: * -> *) a. Monad m => a -> m a
return (HasDebugCallStack => Role -> Int -> KindCoercion -> KindCoercion
Role -> Int -> KindCoercion -> KindCoercion
mkNthCo Role
r Int
n KindCoercion
co') }
    go_co (VarSet, VarEnv TyVar)
cxt (LRCo LeftOrRight
lr KindCoercion
co)              = do { KindCoercion
co' <- (VarSet, VarEnv TyVar) -> KindCoercion -> Maybe KindCoercion
go_co (VarSet, VarEnv TyVar)
cxt KindCoercion
co
                                             ; KindCoercion -> Maybe KindCoercion
forall (m :: * -> *) a. Monad m => a -> m a
return (LeftOrRight -> KindCoercion -> KindCoercion
mkLRCo LeftOrRight
lr KindCoercion
co') }
    go_co (VarSet, VarEnv TyVar)
cxt (InstCo KindCoercion
co KindCoercion
arg)           = do { KindCoercion
co' <- (VarSet, VarEnv TyVar) -> KindCoercion -> Maybe KindCoercion
go_co (VarSet, VarEnv TyVar)
cxt KindCoercion
co
                                             ; KindCoercion
arg' <- (VarSet, VarEnv TyVar) -> KindCoercion -> Maybe KindCoercion
go_co (VarSet, VarEnv TyVar)
cxt KindCoercion
arg
                                             ; KindCoercion -> Maybe KindCoercion
forall (m :: * -> *) a. Monad m => a -> m a
return (KindCoercion -> KindCoercion -> KindCoercion
mkInstCo KindCoercion
co' KindCoercion
arg') }
    go_co (VarSet, VarEnv TyVar)
cxt (KindCo KindCoercion
co)               = do { KindCoercion
co' <- (VarSet, VarEnv TyVar) -> KindCoercion -> Maybe KindCoercion
go_co (VarSet, VarEnv TyVar)
cxt KindCoercion
co
                                             ; KindCoercion -> Maybe KindCoercion
forall (m :: * -> *) a. Monad m => a -> m a
return (KindCoercion -> KindCoercion
mkKindCo KindCoercion
co') }
    go_co (VarSet, VarEnv TyVar)
cxt (SubCo KindCoercion
co)                = do { KindCoercion
co' <- (VarSet, VarEnv TyVar) -> KindCoercion -> Maybe KindCoercion
go_co (VarSet, VarEnv TyVar)
cxt KindCoercion
co
                                             ; KindCoercion -> Maybe KindCoercion
forall (m :: * -> *) a. Monad m => a -> m a
return (KindCoercion -> KindCoercion
mkSubCo KindCoercion
co') }
    go_co (VarSet, VarEnv TyVar)
cxt (AxiomRuleCo CoAxiomRule
ax [KindCoercion]
cs)       = do { [KindCoercion]
cs' <- (KindCoercion -> Maybe KindCoercion)
-> [KindCoercion] -> Maybe [KindCoercion]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM ((VarSet, VarEnv TyVar) -> KindCoercion -> Maybe KindCoercion
go_co (VarSet, VarEnv TyVar)
cxt) [KindCoercion]
cs
                                             ; KindCoercion -> Maybe KindCoercion
forall (m :: * -> *) a. Monad m => a -> m a
return (CoAxiomRule -> [KindCoercion] -> KindCoercion
mkAxiomRuleCo CoAxiomRule
ax [KindCoercion]
cs') }

    ------------------
    go_prov :: (VarSet, VarEnv TyVar)
-> UnivCoProvenance -> Maybe UnivCoProvenance
go_prov (VarSet, VarEnv TyVar)
_   UnivCoProvenance
UnsafeCoerceProv    = UnivCoProvenance -> Maybe UnivCoProvenance
forall (m :: * -> *) a. Monad m => a -> m a
return UnivCoProvenance
UnsafeCoerceProv
    go_prov (VarSet, VarEnv TyVar)
cxt (PhantomProv KindCoercion
co)    = KindCoercion -> UnivCoProvenance
PhantomProv (KindCoercion -> UnivCoProvenance)
-> Maybe KindCoercion -> Maybe UnivCoProvenance
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> (VarSet, VarEnv TyVar) -> KindCoercion -> Maybe KindCoercion
go_co (VarSet, VarEnv TyVar)
cxt KindCoercion
co
    go_prov (VarSet, VarEnv TyVar)
cxt (ProofIrrelProv KindCoercion
co) = KindCoercion -> UnivCoProvenance
ProofIrrelProv (KindCoercion -> UnivCoProvenance)
-> Maybe KindCoercion -> Maybe UnivCoProvenance
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> (VarSet, VarEnv TyVar) -> KindCoercion -> Maybe KindCoercion
go_co (VarSet, VarEnv TyVar)
cxt KindCoercion
co
    go_prov (VarSet, VarEnv TyVar)
_   p :: UnivCoProvenance
p@(PluginProv String
_)    = UnivCoProvenance -> Maybe UnivCoProvenance
forall (m :: * -> *) a. Monad m => a -> m a
return UnivCoProvenance
p


{-
%************************************************************************
%*                                                                      *
        Miscellaneous functions
%*                                                                      *
%************************************************************************

-}
-- | All type constructors occurring in the type; looking through type
--   synonyms, but not newtypes.
--  When it finds a Class, it returns the class TyCon.
tyConsOfType :: Type -> UniqSet TyCon
tyConsOfType :: Type -> UniqSet TyCon
tyConsOfType Type
ty
  = Type -> UniqSet TyCon
go Type
ty
  where
     go :: Type -> UniqSet TyCon  -- The UniqSet does duplicate elim
     go :: Type -> UniqSet TyCon
go Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> UniqSet TyCon
go Type
ty'
     go (TyVarTy {})                = UniqSet TyCon
forall a. UniqSet a
emptyUniqSet
     go (LitTy {})                  = UniqSet TyCon
forall a. UniqSet a
emptyUniqSet
     go (TyConApp TyCon
tc [Type]
tys)           = TyCon -> UniqSet TyCon
forall a. Uniquable a => a -> UniqSet a
go_tc TyCon
tc UniqSet TyCon -> UniqSet TyCon -> UniqSet TyCon
forall a. UniqSet a -> UniqSet a -> UniqSet a
`unionUniqSets` [Type] -> UniqSet TyCon
forall (t :: * -> *). Foldable t => t Type -> UniqSet TyCon
go_s [Type]
tys
     go (AppTy Type
a Type
b)                 = Type -> UniqSet TyCon
go Type
a UniqSet TyCon -> UniqSet TyCon -> UniqSet TyCon
forall a. UniqSet a -> UniqSet a -> UniqSet a
`unionUniqSets` Type -> UniqSet TyCon
go Type
b
     go (FunTy AnonArgFlag
_ Type
a Type
b)               = Type -> UniqSet TyCon
go Type
a UniqSet TyCon -> UniqSet TyCon -> UniqSet TyCon
forall a. UniqSet a -> UniqSet a -> UniqSet a
`unionUniqSets` Type -> UniqSet TyCon
go Type
b UniqSet TyCon -> UniqSet TyCon -> UniqSet TyCon
forall a. UniqSet a -> UniqSet a -> UniqSet a
`unionUniqSets` TyCon -> UniqSet TyCon
forall a. Uniquable a => a -> UniqSet a
go_tc TyCon
funTyCon
     go (ForAllTy (Bndr TyVar
tv ArgFlag
_) Type
ty)   = Type -> UniqSet TyCon
go Type
ty UniqSet TyCon -> UniqSet TyCon -> UniqSet TyCon
forall a. UniqSet a -> UniqSet a -> UniqSet a
`unionUniqSets` Type -> UniqSet TyCon
go (TyVar -> Type
varType TyVar
tv)
     go (CastTy Type
ty KindCoercion
co)              = Type -> UniqSet TyCon
go Type
ty UniqSet TyCon -> UniqSet TyCon -> UniqSet TyCon
forall a. UniqSet a -> UniqSet a -> UniqSet a
`unionUniqSets` KindCoercion -> UniqSet TyCon
go_co KindCoercion
co
     go (CoercionTy KindCoercion
co)             = KindCoercion -> UniqSet TyCon
go_co KindCoercion
co

     go_co :: KindCoercion -> UniqSet TyCon
go_co (Refl Type
ty)               = Type -> UniqSet TyCon
go Type
ty
     go_co (GRefl Role
_ Type
ty MCoercionN
mco)        = Type -> UniqSet TyCon
go Type
ty UniqSet TyCon -> UniqSet TyCon -> UniqSet TyCon
forall a. UniqSet a -> UniqSet a -> UniqSet a
`unionUniqSets` MCoercionN -> UniqSet TyCon
go_mco MCoercionN
mco
     go_co (TyConAppCo Role
_ TyCon
tc [KindCoercion]
args)  = TyCon -> UniqSet TyCon
forall a. Uniquable a => a -> UniqSet a
go_tc TyCon
tc UniqSet TyCon -> UniqSet TyCon -> UniqSet TyCon
forall a. UniqSet a -> UniqSet a -> UniqSet a
`unionUniqSets` [KindCoercion] -> UniqSet TyCon
go_cos [KindCoercion]
args
     go_co (AppCo KindCoercion
co KindCoercion
arg)          = KindCoercion -> UniqSet TyCon
go_co KindCoercion
co UniqSet TyCon -> UniqSet TyCon -> UniqSet TyCon
forall a. UniqSet a -> UniqSet a -> UniqSet a
`unionUniqSets` KindCoercion -> UniqSet TyCon
go_co KindCoercion
arg
     go_co (ForAllCo TyVar
_ KindCoercion
kind_co KindCoercion
co) = KindCoercion -> UniqSet TyCon
go_co KindCoercion
kind_co UniqSet TyCon -> UniqSet TyCon -> UniqSet TyCon
forall a. UniqSet a -> UniqSet a -> UniqSet a
`unionUniqSets` KindCoercion -> UniqSet TyCon
go_co KindCoercion
co
     go_co (FunCo Role
_ KindCoercion
co1 KindCoercion
co2)       = KindCoercion -> UniqSet TyCon
go_co KindCoercion
co1 UniqSet TyCon -> UniqSet TyCon -> UniqSet TyCon
forall a. UniqSet a -> UniqSet a -> UniqSet a
`unionUniqSets` KindCoercion -> UniqSet TyCon
go_co KindCoercion
co2
     go_co (AxiomInstCo CoAxiom Branched
ax Int
_ [KindCoercion]
args) = CoAxiom Branched -> UniqSet TyCon
forall (br :: BranchFlag). CoAxiom br -> UniqSet TyCon
go_ax CoAxiom Branched
ax UniqSet TyCon -> UniqSet TyCon -> UniqSet TyCon
forall a. UniqSet a -> UniqSet a -> UniqSet a
`unionUniqSets` [KindCoercion] -> UniqSet TyCon
go_cos [KindCoercion]
args
     go_co (UnivCo UnivCoProvenance
p Role
_ Type
t1 Type
t2)      = UnivCoProvenance -> UniqSet TyCon
go_prov UnivCoProvenance
p UniqSet TyCon -> UniqSet TyCon -> UniqSet TyCon
forall a. UniqSet a -> UniqSet a -> UniqSet a
`unionUniqSets` Type -> UniqSet TyCon
go Type
t1 UniqSet TyCon -> UniqSet TyCon -> UniqSet TyCon
forall a. UniqSet a -> UniqSet a -> UniqSet a
`unionUniqSets` Type -> UniqSet TyCon
go Type
t2
     go_co (CoVarCo {})            = UniqSet TyCon
forall a. UniqSet a
emptyUniqSet
     go_co (HoleCo {})             = UniqSet TyCon
forall a. UniqSet a
emptyUniqSet
     go_co (SymCo KindCoercion
co)              = KindCoercion -> UniqSet TyCon
go_co KindCoercion
co
     go_co (TransCo KindCoercion
co1 KindCoercion
co2)       = KindCoercion -> UniqSet TyCon
go_co KindCoercion
co1 UniqSet TyCon -> UniqSet TyCon -> UniqSet TyCon
forall a. UniqSet a -> UniqSet a -> UniqSet a
`unionUniqSets` KindCoercion -> UniqSet TyCon
go_co KindCoercion
co2
     go_co (NthCo Role
_ Int
_ KindCoercion
co)          = KindCoercion -> UniqSet TyCon
go_co KindCoercion
co
     go_co (LRCo LeftOrRight
_ KindCoercion
co)             = KindCoercion -> UniqSet TyCon
go_co KindCoercion
co
     go_co (InstCo KindCoercion
co KindCoercion
arg)         = KindCoercion -> UniqSet TyCon
go_co KindCoercion
co UniqSet TyCon -> UniqSet TyCon -> UniqSet TyCon
forall a. UniqSet a -> UniqSet a -> UniqSet a
`unionUniqSets` KindCoercion -> UniqSet TyCon
go_co KindCoercion
arg
     go_co (KindCo KindCoercion
co)             = KindCoercion -> UniqSet TyCon
go_co KindCoercion
co
     go_co (SubCo KindCoercion
co)              = KindCoercion -> UniqSet TyCon
go_co KindCoercion
co
     go_co (AxiomRuleCo CoAxiomRule
_ [KindCoercion]
cs)      = [KindCoercion] -> UniqSet TyCon
go_cos [KindCoercion]
cs

     go_mco :: MCoercionN -> UniqSet TyCon
go_mco MCoercionN
MRefl    = UniqSet TyCon
forall a. UniqSet a
emptyUniqSet
     go_mco (MCo KindCoercion
co) = KindCoercion -> UniqSet TyCon
go_co KindCoercion
co

     go_prov :: UnivCoProvenance -> UniqSet TyCon
go_prov UnivCoProvenance
UnsafeCoerceProv    = UniqSet TyCon
forall a. UniqSet a
emptyUniqSet
     go_prov (PhantomProv KindCoercion
co)    = KindCoercion -> UniqSet TyCon
go_co KindCoercion
co
     go_prov (ProofIrrelProv KindCoercion
co) = KindCoercion -> UniqSet TyCon
go_co KindCoercion
co
     go_prov (PluginProv String
_)      = UniqSet TyCon
forall a. UniqSet a
emptyUniqSet
        -- this last case can happen from the tyConsOfType used from
        -- checkTauTvUpdate

     go_s :: t Type -> UniqSet TyCon
go_s t Type
tys     = (Type -> UniqSet TyCon -> UniqSet TyCon)
-> UniqSet TyCon -> t Type -> UniqSet TyCon
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr (UniqSet TyCon -> UniqSet TyCon -> UniqSet TyCon
forall a. UniqSet a -> UniqSet a -> UniqSet a
unionUniqSets (UniqSet TyCon -> UniqSet TyCon -> UniqSet TyCon)
-> (Type -> UniqSet TyCon)
-> Type
-> UniqSet TyCon
-> UniqSet TyCon
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Type -> UniqSet TyCon
go)     UniqSet TyCon
forall a. UniqSet a
emptyUniqSet t Type
tys
     go_cos :: [KindCoercion] -> UniqSet TyCon
go_cos [KindCoercion]
cos   = (KindCoercion -> UniqSet TyCon -> UniqSet TyCon)
-> UniqSet TyCon -> [KindCoercion] -> UniqSet TyCon
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr (UniqSet TyCon -> UniqSet TyCon -> UniqSet TyCon
forall a. UniqSet a -> UniqSet a -> UniqSet a
unionUniqSets (UniqSet TyCon -> UniqSet TyCon -> UniqSet TyCon)
-> (KindCoercion -> UniqSet TyCon)
-> KindCoercion
-> UniqSet TyCon
-> UniqSet TyCon
forall b c a. (b -> c) -> (a -> b) -> a -> c
. KindCoercion -> UniqSet TyCon
go_co)  UniqSet TyCon
forall a. UniqSet a
emptyUniqSet [KindCoercion]
cos

     go_tc :: a -> UniqSet a
go_tc a
tc = a -> UniqSet a
forall a. Uniquable a => a -> UniqSet a
unitUniqSet a
tc
     go_ax :: CoAxiom br -> UniqSet TyCon
go_ax CoAxiom br
ax = TyCon -> UniqSet TyCon
forall a. Uniquable a => a -> UniqSet a
go_tc (TyCon -> UniqSet TyCon) -> TyCon -> UniqSet TyCon
forall a b. (a -> b) -> a -> b
$ CoAxiom br -> TyCon
forall (br :: BranchFlag). CoAxiom br -> TyCon
coAxiomTyCon CoAxiom br
ax

-- | Find the result 'Kind' of a type synonym,
-- after applying it to its 'arity' number of type variables
-- Actually this function works fine on data types too,
-- but they'd always return '*', so we never need to ask
synTyConResKind :: TyCon -> Kind
synTyConResKind :: TyCon -> Type
synTyConResKind TyCon
tycon = HasDebugCallStack => Type -> [Type] -> Type
Type -> [Type] -> Type
piResultTys (TyCon -> Type
tyConKind TyCon
tycon) ([TyVar] -> [Type]
mkTyVarTys (TyCon -> [TyVar]
tyConTyVars TyCon
tycon))

-- | Retrieve the free variables in this type, splitting them based
-- on whether they are used visibly or invisibly. Invisible ones come
-- first.
splitVisVarsOfType :: Type -> Pair TyCoVarSet
splitVisVarsOfType :: Type -> Pair VarSet
splitVisVarsOfType Type
orig_ty = VarSet -> VarSet -> Pair VarSet
forall a. a -> a -> Pair a
Pair VarSet
invis_vars VarSet
vis_vars
  where
    Pair VarSet
invis_vars1 VarSet
vis_vars = Type -> Pair VarSet
go Type
orig_ty
    invis_vars :: VarSet
invis_vars = VarSet
invis_vars1 VarSet -> VarSet -> VarSet
`minusVarSet` VarSet
vis_vars

    go :: Type -> Pair VarSet
go (TyVarTy TyVar
tv)      = VarSet -> VarSet -> Pair VarSet
forall a. a -> a -> Pair a
Pair (Type -> VarSet
tyCoVarsOfType (Type -> VarSet) -> Type -> VarSet
forall a b. (a -> b) -> a -> b
$ TyVar -> Type
tyVarKind TyVar
tv) (TyVar -> VarSet
unitVarSet TyVar
tv)
    go (AppTy Type
t1 Type
t2)     = Type -> Pair VarSet
go Type
t1 Pair VarSet -> Pair VarSet -> Pair VarSet
forall a. Monoid a => a -> a -> a
`mappend` Type -> Pair VarSet
go Type
t2
    go (TyConApp TyCon
tc [Type]
tys) = TyCon -> [Type] -> Pair VarSet
go_tc TyCon
tc [Type]
tys
    go (FunTy AnonArgFlag
_ Type
t1 Type
t2)   = Type -> Pair VarSet
go Type
t1 Pair VarSet -> Pair VarSet -> Pair VarSet
forall a. Monoid a => a -> a -> a
`mappend` Type -> Pair VarSet
go Type
t2
    go (ForAllTy (Bndr TyVar
tv ArgFlag
_) Type
ty)
      = ((VarSet -> TyVar -> VarSet
`delVarSet` TyVar
tv) (VarSet -> VarSet) -> Pair VarSet -> Pair VarSet
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> Type -> Pair VarSet
go Type
ty) Pair VarSet -> Pair VarSet -> Pair VarSet
forall a. Monoid a => a -> a -> a
`mappend`
        (VarSet -> Pair VarSet
invisible (Type -> VarSet
tyCoVarsOfType (Type -> VarSet) -> Type -> VarSet
forall a b. (a -> b) -> a -> b
$ TyVar -> Type
varType TyVar
tv))
    go (LitTy {}) = Pair VarSet
forall a. Monoid a => a
mempty
    go (CastTy Type
ty KindCoercion
co) = Type -> Pair VarSet
go Type
ty Pair VarSet -> Pair VarSet -> Pair VarSet
forall a. Monoid a => a -> a -> a
`mappend` VarSet -> Pair VarSet
invisible (KindCoercion -> VarSet
tyCoVarsOfCo KindCoercion
co)
    go (CoercionTy KindCoercion
co) = VarSet -> Pair VarSet
invisible (VarSet -> Pair VarSet) -> VarSet -> Pair VarSet
forall a b. (a -> b) -> a -> b
$ KindCoercion -> VarSet
tyCoVarsOfCo KindCoercion
co

    invisible :: VarSet -> Pair VarSet
invisible VarSet
vs = VarSet -> VarSet -> Pair VarSet
forall a. a -> a -> Pair a
Pair VarSet
vs VarSet
emptyVarSet

    go_tc :: TyCon -> [Type] -> Pair VarSet
go_tc TyCon
tc [Type]
tys = let ([Type]
invis, [Type]
vis) = TyCon -> [Type] -> ([Type], [Type])
partitionInvisibleTypes TyCon
tc [Type]
tys in
                   VarSet -> Pair VarSet
invisible ([Type] -> VarSet
tyCoVarsOfTypes [Type]
invis) Pair VarSet -> Pair VarSet -> Pair VarSet
forall a. Monoid a => a -> a -> a
`mappend` (Type -> Pair VarSet) -> [Type] -> Pair VarSet
forall (t :: * -> *) m a.
(Foldable t, Monoid m) =>
(a -> m) -> t a -> m
foldMap Type -> Pair VarSet
go [Type]
vis

splitVisVarsOfTypes :: [Type] -> Pair TyCoVarSet
splitVisVarsOfTypes :: [Type] -> Pair VarSet
splitVisVarsOfTypes = (Type -> Pair VarSet) -> [Type] -> Pair VarSet
forall (t :: * -> *) m a.
(Foldable t, Monoid m) =>
(a -> m) -> t a -> m
foldMap Type -> Pair VarSet
splitVisVarsOfType

modifyJoinResTy :: Int            -- Number of binders to skip
                -> (Type -> Type) -- Function to apply to result type
                -> Type           -- Type of join point
                -> Type           -- New type
-- INVARIANT: If any of the first n binders are foralls, those tyvars cannot
-- appear in the original result type. See isValidJoinPointType.
modifyJoinResTy :: Int -> (Type -> Type) -> Type -> Type
modifyJoinResTy Int
orig_ar Type -> Type
f Type
orig_ty
  = Int -> Type -> Type
forall t. (Eq t, Num t) => t -> Type -> Type
go Int
orig_ar Type
orig_ty
  where
    go :: t -> Type -> Type
go t
0 Type
ty = Type -> Type
f Type
ty
    go t
n Type
ty | Just (TyCoBinder
arg_bndr, Type
res_ty) <- Type -> Maybe (TyCoBinder, Type)
splitPiTy_maybe Type
ty
            = TyCoBinder -> Type -> Type
mkPiTy TyCoBinder
arg_bndr (t -> Type -> Type
go (t
nt -> t -> t
forall a. Num a => a -> a -> a
-t
1) Type
res_ty)
            | Bool
otherwise
            = String -> SDoc -> Type
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"modifyJoinResTy" (Int -> SDoc
forall a. Outputable a => a -> SDoc
ppr Int
orig_ar SDoc -> SDoc -> SDoc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
orig_ty)

setJoinResTy :: Int  -- Number of binders to skip
             -> Type -- New result type
             -> Type -- Type of join point
             -> Type -- New type
-- INVARIANT: Same as for modifyJoinResTy
setJoinResTy :: Int -> Type -> Type -> Type
setJoinResTy Int
ar Type
new_res_ty Type
ty
  = Int -> (Type -> Type) -> Type -> Type
modifyJoinResTy Int
ar (Type -> Type -> Type
forall a b. a -> b -> a
const Type
new_res_ty) Type
ty

{-
************************************************************************
*                                                                      *
        Functions over Kinds
*                                                                      *
************************************************************************

Note [Kind Constraint and kind Type]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The kind Constraint is the kind of classes and other type constraints.
The special thing about types of kind Constraint is that
 * They are displayed with double arrow:
     f :: Ord a => a -> a
 * They are implicitly instantiated at call sites; so the type inference
   engine inserts an extra argument of type (Ord a) at every call site
   to f.

However, once type inference is over, there is *no* distinction between
Constraint and Type. Indeed we can have coercions between the two. Consider
   class C a where
     op :: a -> a
For this single-method class we may generate a newtype, which in turn
generates an axiom witnessing
    C a ~ (a -> a)
so on the left we have Constraint, and on the right we have Type.
See #7451.

Bottom line: although 'Type' and 'Constraint' are distinct TyCons, with
distinct uniques, they are treated as equal at all times except
during type inference.
-}

isConstraintKindCon :: TyCon -> Bool
isConstraintKindCon :: TyCon -> Bool
isConstraintKindCon TyCon
tc = TyCon -> Unique
tyConUnique TyCon
tc Unique -> Unique -> Bool
forall a. Eq a => a -> a -> Bool
== Unique
constraintKindTyConKey

-- | Tests whether the given kind (which should look like @TYPE x@)
-- is something other than a constructor tree (that is, constructors at every node).
-- E.g.  True of   TYPE k, TYPE (F Int)
--       False of  TYPE 'LiftedRep
isKindLevPoly :: Kind -> Bool
isKindLevPoly :: Type -> Bool
isKindLevPoly Type
k = ASSERT2( isLiftedTypeKind k || _is_type, ppr k )
                    -- the isLiftedTypeKind check is necessary b/c of Constraint
                  Type -> Bool
go Type
k
  where
    go :: Type -> Bool
go Type
ty | Just Type
ty' <- Type -> Maybe Type
coreView Type
ty = Type -> Bool
go Type
ty'
    go TyVarTy{}         = Bool
True
    go AppTy{}           = Bool
True  -- it can't be a TyConApp
    go (TyConApp TyCon
tc [Type]
tys) = TyCon -> Bool
isFamilyTyCon TyCon
tc Bool -> Bool -> Bool
|| (Type -> Bool) -> [Type] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
any Type -> Bool
go [Type]
tys
    go ForAllTy{}        = Bool
True
    go (FunTy AnonArgFlag
_ Type
t1 Type
t2)   = Type -> Bool
go Type
t1 Bool -> Bool -> Bool
|| Type -> Bool
go Type
t2
    go LitTy{}           = Bool
False
    go CastTy{}          = Bool
True
    go CoercionTy{}      = Bool
True

    _is_type :: Bool
_is_type = Type -> Bool
classifiesTypeWithValues Type
k

-----------------------------------------
--              Subkinding
-- The tc variants are used during type-checking, where ConstraintKind
-- is distinct from all other kinds
-- After type-checking (in core), Constraint and liftedTypeKind are
-- indistinguishable

-- | Does this classify a type allowed to have values? Responds True to things
-- like *, #, TYPE Lifted, TYPE v, Constraint.
classifiesTypeWithValues :: Kind -> Bool
-- ^ True of any sub-kind of OpenTypeKind
classifiesTypeWithValues :: Type -> Bool
classifiesTypeWithValues Type
k = Maybe Type -> Bool
forall a. Maybe a -> Bool
isJust (HasDebugCallStack => Type -> Maybe Type
Type -> Maybe Type
kindRep_maybe Type
k)

{-
%************************************************************************
%*                                                                      *
         Pretty-printing
%*                                                                      *
%************************************************************************

Most pretty-printing is either in TyCoRep or IfaceType.

-}

-- | Does a 'TyCon' (that is applied to some number of arguments) need to be
-- ascribed with an explicit kind signature to resolve ambiguity if rendered as
-- a source-syntax type?
-- (See @Note [When does a tycon application need an explicit kind signature?]@
-- for a full explanation of what this function checks for.)
tyConAppNeedsKindSig
  :: Bool  -- ^ Should specified binders count towards injective positions in
           --   the kind of the TyCon? (If you're using visible kind
           --   applications, then you want True here.
  -> TyCon
  -> Int   -- ^ The number of args the 'TyCon' is applied to.
  -> Bool  -- ^ Does @T t_1 ... t_n@ need a kind signature? (Where @n@ is the
           --   number of arguments)
tyConAppNeedsKindSig :: Bool -> TyCon -> Int -> Bool
tyConAppNeedsKindSig Bool
spec_inj_pos TyCon
tc Int
n_args
  | Ordering
LT <- [TyConBinder] -> Int -> Ordering
forall a. [a] -> Int -> Ordering
listLengthCmp [TyConBinder]
tc_binders Int
n_args
  = Bool
False
  | Bool
otherwise
  = let ([TyConBinder]
dropped_binders, [TyConBinder]
remaining_binders)
          = Int -> [TyConBinder] -> ([TyConBinder], [TyConBinder])
forall a. Int -> [a] -> ([a], [a])
splitAt Int
n_args [TyConBinder]
tc_binders
        result_kind :: Type
result_kind  = [TyConBinder] -> Type -> Type
mkTyConKind [TyConBinder]
remaining_binders Type
tc_res_kind
        result_vars :: VarSet
result_vars  = Type -> VarSet
tyCoVarsOfType Type
result_kind
        dropped_vars :: VarSet
dropped_vars = FV -> VarSet
fvVarSet (FV -> VarSet) -> FV -> VarSet
forall a b. (a -> b) -> a -> b
$
                       (TyConBinder -> FV) -> [TyConBinder] -> FV
forall a. (a -> FV) -> [a] -> FV
mapUnionFV TyConBinder -> FV
injective_vars_of_binder [TyConBinder]
dropped_binders

    in Bool -> Bool
not (VarSet -> VarSet -> Bool
subVarSet VarSet
result_vars VarSet
dropped_vars)
  where
    tc_binders :: [TyConBinder]
tc_binders  = TyCon -> [TyConBinder]
tyConBinders TyCon
tc
    tc_res_kind :: Type
tc_res_kind = TyCon -> Type
tyConResKind TyCon
tc

    -- Returns the variables that would be fixed by knowing a TyConBinder. See
    -- Note [When does a tycon application need an explicit kind signature?]
    -- for a more detailed explanation of what this function does.
    injective_vars_of_binder :: TyConBinder -> FV
    injective_vars_of_binder :: TyConBinder -> FV
injective_vars_of_binder (Bndr TyVar
tv TyConBndrVis
vis) =
      case TyConBndrVis
vis of
        AnonTCB AnonArgFlag
VisArg -> Bool -> Type -> FV
injectiveVarsOfType Bool
False -- conservative choice
                                              (TyVar -> Type
varType TyVar
tv)
        NamedTCB ArgFlag
argf  | ArgFlag -> Bool
source_of_injectivity ArgFlag
argf
                       -> TyVar -> FV
unitFV TyVar
tv FV -> FV -> FV
`unionFV`
                          Bool -> Type -> FV
injectiveVarsOfType Bool
False (TyVar -> Type
varType TyVar
tv)
        TyConBndrVis
_              -> FV
emptyFV

    source_of_injectivity :: ArgFlag -> Bool
source_of_injectivity ArgFlag
Required  = Bool
True
    source_of_injectivity ArgFlag
Specified = Bool
spec_inj_pos
    source_of_injectivity ArgFlag
Inferred  = Bool
False

{-
Note [When does a tycon application need an explicit kind signature?]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
There are a couple of places in GHC where we convert Core Types into forms that
more closely resemble user-written syntax. These include:

1. Template Haskell Type reification (see, for instance, TcSplice.reify_tc_app)
2. Converting Types to LHsTypes (in GHC.Hs.Utils.typeToLHsType, or in Haddock)

This conversion presents a challenge: how do we ensure that the resulting type
has enough kind information so as not to be ambiguous? To better motivate this
question, consider the following Core type:

  -- Foo :: Type -> Type
  type Foo = Proxy Type

There is nothing ambiguous about the RHS of Foo in Core. But if we were to,
say, reify it into a TH Type, then it's tempting to just drop the invisible
Type argument and simply return `Proxy`. But now we've lost crucial kind
information: we don't know if we're dealing with `Proxy Type` or `Proxy Bool`
or `Proxy Int` or something else! We've inadvertently introduced ambiguity.

Unlike in other situations in GHC, we can't just turn on
-fprint-explicit-kinds, as we need to produce something which has the same
structure as a source-syntax type. Moreover, we can't rely on visible kind
application, since the first kind argument to Proxy is inferred, not specified.
Our solution is to annotate certain tycons with their kinds whenever they
appear in applied form in order to resolve the ambiguity. For instance, we
would reify the RHS of Foo like so:

  type Foo = (Proxy :: Type -> Type)

We need to devise an algorithm that determines precisely which tycons need
these explicit kind signatures. We certainly don't want to annotate _every_
tycon with a kind signature, or else we might end up with horribly bloated
types like the following:

  (Either :: Type -> Type -> Type) (Int :: Type) (Char :: Type)

We only want to annotate tycons that absolutely require kind signatures in
order to resolve some sort of ambiguity, and nothing more.

Suppose we have a tycon application (T ty_1 ... ty_n). Why might this type
require a kind signature? It might require it when we need to fill in any of
T's omitted arguments. By "omitted argument", we mean one that is dropped when
reifying ty_1 ... ty_n. Sometimes, the omitted arguments are inferred and
specified arguments (e.g., TH reification in TcSplice), and sometimes the
omitted arguments are only the inferred ones (e.g., in GHC.Hs.Utils.typeToLHsType,
which reifies specified arguments through visible kind application).
Regardless, the key idea is that _some_ arguments are going to be omitted after
reification, and the only mechanism we have at our disposal for filling them in
is through explicit kind signatures.

What do we mean by "fill in"? Let's consider this small example:

  T :: forall {k}. Type -> (k -> Type) -> k

Moreover, we have this application of T:

  T @{j} Int aty

When we reify this type, we omit the inferred argument @{j}. Is it fixed by the
other (non-inferred) arguments? Yes! If we know the kind of (aty :: blah), then
we'll generate an equality constraint (kappa -> Type) and, assuming we can
solve it, that will fix `kappa`. (Here, `kappa` is the unification variable
that we instantiate `k` with.)

Therefore, for any application of a tycon T to some arguments, the Question We
Must Answer is:

* Given the first n arguments of T, do the kinds of the non-omitted arguments
  fill in the omitted arguments?

(This is still a bit hand-wavey, but we'll refine this question incrementally
as we explain more of the machinery underlying this process.)

Answering this question is precisely the role that the `injectiveVarsOfType`
and `injective_vars_of_binder` functions exist to serve. If an omitted argument
`a` appears in the set returned by `injectiveVarsOfType ty`, then knowing
`ty` determines (i.e., fills in) `a`. (More on `injective_vars_of_binder` in a
bit.)

More formally, if
`a` is in `injectiveVarsOfType ty`
and  S1(ty) ~ S2(ty),
then S1(a)  ~ S2(a),
where S1 and S2 are arbitrary substitutions.

For example, is `F` is a non-injective type family, then

  injectiveVarsOfType(Either c (Maybe (a, F b c))) = {a, c}

Now that we know what this function does, here is a second attempt at the
Question We Must Answer:

* Given the first n arguments of T (ty_1 ... ty_n), consider the binders
  of T that are instantiated by non-omitted arguments. Do the injective
  variables of these binders fill in the remainder of T's kind?

Alright, we're getting closer. Next, we need to clarify what the injective
variables of a tycon binder are. This the role that the
`injective_vars_of_binder` function serves. Here is what this function does for
each form of tycon binder:

* Anonymous binders are injective positions. For example, in the promoted data
  constructor '(:):

    '(:) :: forall a. a -> [a] -> [a]

  The second and third tyvar binders (of kinds `a` and `[a]`) are both
  anonymous, so if we had '(:) 'True '[], then the kinds of 'True and
  '[] would contribute to the kind of '(:) 'True '[]. Therefore,
  injective_vars_of_binder(_ :: a) = injectiveVarsOfType(a) = {a}.
  (Similarly, injective_vars_of_binder(_ :: [a]) = {a}.)
* Named binders:
  - Inferred binders are never injective positions. For example, in this data
    type:

      data Proxy a
      Proxy :: forall {k}. k -> Type

    If we had Proxy 'True, then the kind of 'True would not contribute to the
    kind of Proxy 'True. Therefore,
    injective_vars_of_binder(forall {k}. ...) = {}.
  - Required binders are injective positions. For example, in this data type:

      data Wurble k (a :: k) :: k
      Wurble :: forall k -> k -> k

  The first tyvar binder (of kind `forall k`) has required visibility, so if
  we had Wurble (Maybe a) Nothing, then the kind of Maybe a would
  contribute to the kind of Wurble (Maybe a) Nothing. Hence,
  injective_vars_of_binder(forall a -> ...) = {a}.
  - Specified binders /might/ be injective positions, depending on how you
    approach things. Continuing the '(:) example:

      '(:) :: forall a. a -> [a] -> [a]

    Normally, the (forall a. ...) tyvar binder wouldn't contribute to the kind
    of '(:) 'True '[], since it's not explicitly instantiated by the user. But
    if visible kind application is enabled, then this is possible, since the
    user can write '(:) @Bool 'True '[]. (In that case,
    injective_vars_of_binder(forall a. ...) = {a}.)

    There are some situations where using visible kind application is appropriate
    (e.g., GHC.Hs.Utils.typeToLHsType) and others where it is not (e.g., TH
    reification), so the `injective_vars_of_binder` function is parametrized by
    a Bool which decides if specified binders should be counted towards
    injective positions or not.

Now that we've defined injective_vars_of_binder, we can refine the Question We
Must Answer once more:

* Given the first n arguments of T (ty_1 ... ty_n), consider the binders
  of T that are instantiated by non-omitted arguments. For each such binder
  b_i, take the union of all injective_vars_of_binder(b_i). Is this set a
  superset of the free variables of the remainder of T's kind?

If the answer to this question is "no", then (T ty_1 ... ty_n) needs an
explicit kind signature, since T's kind has kind variables leftover that
aren't fixed by the non-omitted arguments.

One last sticking point: what does "the remainder of T's kind" mean? You might
be tempted to think that it corresponds to all of the arguments in the kind of
T that would normally be instantiated by omitted arguments. But this isn't
quite right, strictly speaking. Consider the following (silly) example:

  S :: forall {k}. Type -> Type

And suppose we have this application of S:

  S Int Bool

The Int argument would be omitted, and
injective_vars_of_binder(_ :: Type) = {}. This is not a superset of {k}, which
might suggest that (S Bool) needs an explicit kind signature. But
(S Bool :: Type) doesn't actually fix `k`! This is because the kind signature
only affects the /result/ of the application, not all of the individual
arguments. So adding a kind signature here won't make a difference. Therefore,
the fourth (and final) iteration of the Question We Must Answer is:

* Given the first n arguments of T (ty_1 ... ty_n), consider the binders
  of T that are instantiated by non-omitted arguments. For each such binder
  b_i, take the union of all injective_vars_of_binder(b_i). Is this set a
  superset of the free variables of the kind of (T ty_1 ... ty_n)?

Phew, that was a lot of work!

How can be sure that this is correct? That is, how can we be sure that in the
event that we leave off a kind annotation, that one could infer the kind of the
tycon application from its arguments? It's essentially a proof by induction: if
we can infer the kinds of every subtree of a type, then the whole tycon
application will have an inferrable kind--unless, of course, the remainder of
the tycon application's kind has uninstantiated kind variables.

What happens if T is oversaturated? That is, if T's kind has fewer than n
arguments, in the case that the concrete application instantiates a result
kind variable with an arrow kind? If we run out of arguments, we do not attach
a kind annotation. This should be a rare case, indeed. Here is an example:

   data T1 :: k1 -> k2 -> *
   data T2 :: k1 -> k2 -> *

   type family G (a :: k) :: k
   type instance G T1 = T2

   type instance F Char = (G T1 Bool :: (* -> *) -> *)   -- F from above

Here G's kind is (forall k. k -> k), and the desugared RHS of that last
instance of F is (G (* -> (* -> *) -> *) (T1 * (* -> *)) Bool). According to
the algorithm above, there are 3 arguments to G so we should peel off 3
arguments in G's kind. But G's kind has only two arguments. This is the
rare special case, and we choose not to annotate the application of G with
a kind signature. After all, we needn't do this, since that instance would
be reified as:

   type instance F Char = G (T1 :: * -> (* -> *) -> *) Bool

So the kind of G isn't ambiguous anymore due to the explicit kind annotation
on its argument. See #8953 and test th/T8953.
-}