{- (c) The University of Glasgow 2006 (c) The AQUA Project, Glasgow University, 1996-1998 TcHsSyn: Specialisations of the @HsSyn@ syntax for the typechecker This module is an extension of @HsSyn@ syntax, for use in the type checker. -} {-# LANGUAGE CPP, TupleSections #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE ViewPatterns #-} module TcHsSyn ( -- * Extracting types from HsSyn hsLitType, hsPatType, hsLPatType, -- * Other HsSyn functions mkHsDictLet, mkHsApp, mkHsAppTy, mkHsCaseAlt, shortCutLit, hsOverLitName, conLikeResTy, -- * re-exported from TcMonad TcId, TcIdSet, -- * Zonking -- | For a description of "zonking", see Note [What is zonking?] -- in TcMType zonkTopDecls, zonkTopExpr, zonkTopLExpr, zonkTopBndrs, ZonkEnv, ZonkFlexi(..), emptyZonkEnv, mkEmptyZonkEnv, initZonkEnv, zonkTyVarBinders, zonkTyVarBindersX, zonkTyVarBinderX, zonkTyBndrs, zonkTyBndrsX, zonkTcTypeToType, zonkTcTypeToTypeX, zonkTcTypesToTypes, zonkTcTypesToTypesX, zonkTyVarOcc, zonkCoToCo, zonkEvBinds, zonkTcEvBinds, zonkTcMethInfoToMethInfoX, lookupTyVarOcc ) where #include "HsVersions.h" import GhcPrelude import GHC.Hs import Id import IdInfo import Predicate import TcRnMonad import PrelNames import BuildTyCl ( TcMethInfo, MethInfo ) import TcType import TcMType import TcEnv ( tcLookupGlobalOnly ) import TcEvidence import TyCoPpr ( pprTyVar ) import TysPrim import TyCon import TysWiredIn import Type import Coercion import ConLike import DataCon import HscTypes import Name import NameEnv import Var import VarEnv import DynFlags import Literal import BasicTypes import Maybes import SrcLoc import Bag import Outputable import Util import UniqFM import CoreSyn import {-# SOURCE #-} TcSplice (runTopSplice) import Control.Monad import Data.List ( partition ) import Control.Arrow ( second ) {- ************************************************************************ * * Extracting the type from HsSyn * * ************************************************************************ -} hsLPatType :: LPat GhcTc -> Type hsLPatType (dL->L _ p) = hsPatType p hsPatType :: Pat GhcTc -> Type hsPatType (ParPat _ pat) = hsLPatType pat hsPatType (WildPat ty) = ty hsPatType (VarPat _ lvar) = idType (unLoc lvar) hsPatType (BangPat _ pat) = hsLPatType pat hsPatType (LazyPat _ pat) = hsLPatType pat hsPatType (LitPat _ lit) = hsLitType lit hsPatType (AsPat _ var _) = idType (unLoc var) hsPatType (ViewPat ty _ _) = ty hsPatType (ListPat (ListPatTc ty Nothing) _) = mkListTy ty hsPatType (ListPat (ListPatTc _ (Just (ty,_))) _) = ty hsPatType (TuplePat tys _ bx) = mkTupleTy1 bx tys -- See Note [Don't flatten tuples from HsSyn] in MkCore hsPatType (SumPat tys _ _ _ ) = mkSumTy tys hsPatType (ConPatOut { pat_con = lcon , pat_arg_tys = tys }) = conLikeResTy (unLoc lcon) tys hsPatType (SigPat ty _ _) = ty hsPatType (NPat ty _ _ _) = ty hsPatType (NPlusKPat ty _ _ _ _ _) = ty hsPatType (CoPat _ _ _ ty) = ty hsPatType (XPat n) = noExtCon n hsPatType ConPatIn{} = panic "hsPatType: ConPatIn" hsPatType SplicePat{} = panic "hsPatType: SplicePat" hsLitType :: HsLit (GhcPass p) -> TcType hsLitType (HsChar _ _) = charTy hsLitType (HsCharPrim _ _) = charPrimTy hsLitType (HsString _ _) = stringTy hsLitType (HsStringPrim _ _) = addrPrimTy hsLitType (HsInt _ _) = intTy hsLitType (HsIntPrim _ _) = intPrimTy hsLitType (HsWordPrim _ _) = wordPrimTy hsLitType (HsInt64Prim _ _) = int64PrimTy hsLitType (HsWord64Prim _ _) = word64PrimTy hsLitType (HsInteger _ _ ty) = ty hsLitType (HsRat _ _ ty) = ty hsLitType (HsFloatPrim _ _) = floatPrimTy hsLitType (HsDoublePrim _ _) = doublePrimTy hsLitType (XLit nec) = noExtCon nec -- Overloaded literals. Here mainly because it uses isIntTy etc shortCutLit :: DynFlags -> OverLitVal -> TcType -> Maybe (HsExpr GhcTcId) shortCutLit dflags (HsIntegral int@(IL src neg i)) ty | isIntTy ty && inIntRange dflags i = Just (HsLit noExtField (HsInt noExtField int)) | isWordTy ty && inWordRange dflags i = Just (mkLit wordDataCon (HsWordPrim src i)) | isIntegerTy ty = Just (HsLit noExtField (HsInteger src i ty)) | otherwise = shortCutLit dflags (HsFractional (integralFractionalLit neg i)) ty -- The 'otherwise' case is important -- Consider (3 :: Float). Syntactically it looks like an IntLit, -- so we'll call shortCutIntLit, but of course it's a float -- This can make a big difference for programs with a lot of -- literals, compiled without -O shortCutLit _ (HsFractional f) ty | isFloatTy ty = Just (mkLit floatDataCon (HsFloatPrim noExtField f)) | isDoubleTy ty = Just (mkLit doubleDataCon (HsDoublePrim noExtField f)) | otherwise = Nothing shortCutLit _ (HsIsString src s) ty | isStringTy ty = Just (HsLit noExtField (HsString src s)) | otherwise = Nothing mkLit :: DataCon -> HsLit GhcTc -> HsExpr GhcTc mkLit con lit = HsApp noExtField (nlHsDataCon con) (nlHsLit lit) ------------------------------ hsOverLitName :: OverLitVal -> Name -- Get the canonical 'fromX' name for a particular OverLitVal hsOverLitName (HsIntegral {}) = fromIntegerName hsOverLitName (HsFractional {}) = fromRationalName hsOverLitName (HsIsString {}) = fromStringName {- ************************************************************************ * * \subsection[BackSubst-HsBinds]{Running a substitution over @HsBinds@} * * ************************************************************************ The rest of the zonking is done *after* typechecking. The main zonking pass runs over the bindings a) to convert TcTyVars to TyVars etc, dereferencing any bindings etc b) convert unbound TcTyVar to Void c) convert each TcId to an Id by zonking its type The type variables are converted by binding mutable tyvars to immutable ones and then zonking as normal. The Ids are converted by binding them in the normal Tc envt; that way we maintain sharing; eg an Id is zonked at its binding site and they all occurrences of that Id point to the common zonked copy It's all pretty boring stuff, because HsSyn is such a large type, and the environment manipulation is tiresome. -} -- Confused by zonking? See Note [What is zonking?] in TcMType. -- | See Note [The ZonkEnv] -- Confused by zonking? See Note [What is zonking?] in TcMType. data ZonkEnv -- See Note [The ZonkEnv] = ZonkEnv { ze_flexi :: ZonkFlexi , ze_tv_env :: TyCoVarEnv TyCoVar , ze_id_env :: IdEnv Id , ze_meta_tv_env :: TcRef (TyVarEnv Type) } {- Note [The ZonkEnv] ~~~~~~~~~~~~~~~~~~~~~ * ze_flexi :: ZonkFlexi says what to do with a unification variable that is still un-unified. See Note [Un-unified unification variables] * ze_tv_env :: TyCoVarEnv TyCoVar promotes sharing. At a binding site of a tyvar or covar, we zonk the kind right away and add a mapping to the env. This prevents re-zonking the kind at every occurrence. But this is *just* an optimisation. * ze_id_env : IdEnv Id promotes sharing among Ids, by making all occurrences of the Id point to a single zonked copy, built at the binding site. Unlike ze_tv_env, it is knot-tied: see extendIdZonkEnvRec. In a mutually recusive group rec { f = ...g...; g = ...f... } we want the occurrence of g to point to the one zonked Id for g, and the same for f. Because it is knot-tied, we must be careful to consult it lazily. Specifically, zonkIdOcc is not monadic. * ze_meta_tv_env: see Note [Sharing when zonking to Type] Notes: * We must be careful never to put coercion variables (which are Ids, after all) in the knot-tied ze_id_env, because coercions can appear in types, and we sometimes inspect a zonked type in this module. [Question: where, precisely?] * In zonkTyVarOcc we consult ze_tv_env in a monadic context, a second reason that ze_tv_env can't be monadic. * An obvious suggestion would be to have one VarEnv Var to replace both ze_id_env and ze_tv_env, but that doesn't work because of the knot-tying stuff mentioned above. Note [Un-unified unification variables] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ What should we do if we find a Flexi unification variable? There are three possibilities: * DefaultFlexi: this is the common case, in situations like length @alpha ([] @alpha) It really doesn't matter what type we choose for alpha. But we must choose a type! We can't leae mutable unification variables floating around: after typecheck is complete, every type variable occurrence must have a bindign site. So we default it to 'Any' of the right kind. All this works for both type and kind variables (indeed the two are the same thign). * SkolemiseFlexi: is a special case for the LHS of RULES. See Note [Zonking the LHS of a RULE] * RuntimeUnkFlexi: is a special case for the GHCi debugger. It's a way to have a variable that is not a mutuable unification variable, but doesn't have a binding site either. -} data ZonkFlexi -- See Note [Un-unified unification variables] = DefaultFlexi -- Default unbound unificaiton variables to Any | SkolemiseFlexi -- Skolemise unbound unification variables -- See Note [Zonking the LHS of a RULE] | RuntimeUnkFlexi -- Used in the GHCi debugger instance Outputable ZonkEnv where ppr (ZonkEnv { ze_tv_env = tv_env , ze_id_env = id_env }) = text "ZE" <+> braces (vcat [ text "ze_tv_env =" <+> ppr tv_env , text "ze_id_env =" <+> ppr id_env ]) -- The EvBinds have to already be zonked, but that's usually the case. emptyZonkEnv :: TcM ZonkEnv emptyZonkEnv = mkEmptyZonkEnv DefaultFlexi mkEmptyZonkEnv :: ZonkFlexi -> TcM ZonkEnv mkEmptyZonkEnv flexi = do { mtv_env_ref <- newTcRef emptyVarEnv ; return (ZonkEnv { ze_flexi = flexi , ze_tv_env = emptyVarEnv , ze_id_env = emptyVarEnv , ze_meta_tv_env = mtv_env_ref }) } initZonkEnv :: (ZonkEnv -> TcM b) -> TcM b initZonkEnv thing_inside = do { ze <- mkEmptyZonkEnv DefaultFlexi ; thing_inside ze } -- | Extend the knot-tied environment. extendIdZonkEnvRec :: ZonkEnv -> [Var] -> ZonkEnv extendIdZonkEnvRec ze@(ZonkEnv { ze_id_env = id_env }) ids -- NB: Don't look at the var to decide which env't to put it in. That -- would end up knot-tying all the env'ts. = ze { ze_id_env = extendVarEnvList id_env [(id,id) | id <- ids] } -- Given coercion variables will actually end up here. That's OK though: -- coercion variables are never looked up in the knot-tied env't, so zonking -- them simply doesn't get optimised. No one gets hurt. An improvement (?) -- would be to do SCC analysis in zonkEvBinds and then only knot-tie the -- recursive groups. But perhaps the time it takes to do the analysis is -- more than the savings. extendZonkEnv :: ZonkEnv -> [Var] -> ZonkEnv extendZonkEnv ze@(ZonkEnv { ze_tv_env = tyco_env, ze_id_env = id_env }) vars = ze { ze_tv_env = extendVarEnvList tyco_env [(tv,tv) | tv <- tycovars] , ze_id_env = extendVarEnvList id_env [(id,id) | id <- ids] } where (tycovars, ids) = partition isTyCoVar vars extendIdZonkEnv :: ZonkEnv -> Var -> ZonkEnv extendIdZonkEnv ze@(ZonkEnv { ze_id_env = id_env }) id = ze { ze_id_env = extendVarEnv id_env id id } extendTyZonkEnv :: ZonkEnv -> TyVar -> ZonkEnv extendTyZonkEnv ze@(ZonkEnv { ze_tv_env = ty_env }) tv = ze { ze_tv_env = extendVarEnv ty_env tv tv } setZonkType :: ZonkEnv -> ZonkFlexi -> ZonkEnv setZonkType ze flexi = ze { ze_flexi = flexi } zonkEnvIds :: ZonkEnv -> TypeEnv zonkEnvIds (ZonkEnv { ze_id_env = id_env}) = mkNameEnv [(getName id, AnId id) | id <- nonDetEltsUFM id_env] -- It's OK to use nonDetEltsUFM here because we forget the ordering -- immediately by creating a TypeEnv zonkLIdOcc :: ZonkEnv -> Located TcId -> Located Id zonkLIdOcc env = onHasSrcSpan (zonkIdOcc env) zonkIdOcc :: ZonkEnv -> TcId -> Id -- Ids defined in this module should be in the envt; -- ignore others. (Actually, data constructors are also -- not LocalVars, even when locally defined, but that is fine.) -- (Also foreign-imported things aren't currently in the ZonkEnv; -- that's ok because they don't need zonking.) -- -- Actually, Template Haskell works in 'chunks' of declarations, and -- an earlier chunk won't be in the 'env' that the zonking phase -- carries around. Instead it'll be in the tcg_gbl_env, already fully -- zonked. There's no point in looking it up there (except for error -- checking), and it's not conveniently to hand; hence the simple -- 'orElse' case in the LocalVar branch. -- -- Even without template splices, in module Main, the checking of -- 'main' is done as a separate chunk. zonkIdOcc (ZonkEnv { ze_id_env = id_env}) id | isLocalVar id = lookupVarEnv id_env id `orElse` id | otherwise = id zonkIdOccs :: ZonkEnv -> [TcId] -> [Id] zonkIdOccs env ids = map (zonkIdOcc env) ids -- zonkIdBndr is used *after* typechecking to get the Id's type -- to its final form. The TyVarEnv give zonkIdBndr :: ZonkEnv -> TcId -> TcM Id zonkIdBndr env v = do ty' <- zonkTcTypeToTypeX env (idType v) ensureNotLevPoly ty' (text "In the type of binder" <+> quotes (ppr v)) return (modifyIdInfo (`setLevityInfoWithType` ty') (setIdType v ty')) zonkIdBndrs :: ZonkEnv -> [TcId] -> TcM [Id] zonkIdBndrs env ids = mapM (zonkIdBndr env) ids zonkTopBndrs :: [TcId] -> TcM [Id] zonkTopBndrs ids = initZonkEnv $ \ ze -> zonkIdBndrs ze ids zonkFieldOcc :: ZonkEnv -> FieldOcc GhcTcId -> TcM (FieldOcc GhcTc) zonkFieldOcc env (FieldOcc sel lbl) = fmap ((flip FieldOcc) lbl) $ zonkIdBndr env sel zonkFieldOcc _ (XFieldOcc nec) = noExtCon nec zonkEvBndrsX :: ZonkEnv -> [EvVar] -> TcM (ZonkEnv, [Var]) zonkEvBndrsX = mapAccumLM zonkEvBndrX zonkEvBndrX :: ZonkEnv -> EvVar -> TcM (ZonkEnv, EvVar) -- Works for dictionaries and coercions zonkEvBndrX env var = do { var' <- zonkEvBndr env var ; return (extendZonkEnv env [var'], var') } zonkEvBndr :: ZonkEnv -> EvVar -> TcM EvVar -- Works for dictionaries and coercions -- Does not extend the ZonkEnv zonkEvBndr env var = do { let var_ty = varType var ; ty <- {-# SCC "zonkEvBndr_zonkTcTypeToType" #-} zonkTcTypeToTypeX env var_ty ; return (setVarType var ty) } {- zonkEvVarOcc :: ZonkEnv -> EvVar -> TcM EvTerm zonkEvVarOcc env v | isCoVar v = EvCoercion <$> zonkCoVarOcc env v | otherwise = return (EvId $ zonkIdOcc env v) -} zonkCoreBndrX :: ZonkEnv -> Var -> TcM (ZonkEnv, Var) zonkCoreBndrX env v | isId v = do { v' <- zonkIdBndr env v ; return (extendIdZonkEnv env v', v') } | otherwise = zonkTyBndrX env v zonkCoreBndrsX :: ZonkEnv -> [Var] -> TcM (ZonkEnv, [Var]) zonkCoreBndrsX = mapAccumLM zonkCoreBndrX zonkTyBndrs :: [TcTyVar] -> TcM (ZonkEnv, [TyVar]) zonkTyBndrs tvs = initZonkEnv $ \ze -> zonkTyBndrsX ze tvs zonkTyBndrsX :: ZonkEnv -> [TcTyVar] -> TcM (ZonkEnv, [TyVar]) zonkTyBndrsX = mapAccumLM zonkTyBndrX zonkTyBndrX :: ZonkEnv -> TcTyVar -> TcM (ZonkEnv, TyVar) -- This guarantees to return a TyVar (not a TcTyVar) -- then we add it to the envt, so all occurrences are replaced -- -- It does not clone: the new TyVar has the sane Name -- as the old one. This important when zonking the -- TyVarBndrs of a TyCon, whose Names may scope. zonkTyBndrX env tv = ASSERT2( isImmutableTyVar tv, ppr tv <+> dcolon <+> ppr (tyVarKind tv) ) do { ki <- zonkTcTypeToTypeX env (tyVarKind tv) -- Internal names tidy up better, for iface files. ; let tv' = mkTyVar (tyVarName tv) ki ; return (extendTyZonkEnv env tv', tv') } zonkTyVarBinders :: [VarBndr TcTyVar vis] -> TcM (ZonkEnv, [VarBndr TyVar vis]) zonkTyVarBinders tvbs = initZonkEnv $ \ ze -> zonkTyVarBindersX ze tvbs zonkTyVarBindersX :: ZonkEnv -> [VarBndr TcTyVar vis] -> TcM (ZonkEnv, [VarBndr TyVar vis]) zonkTyVarBindersX = mapAccumLM zonkTyVarBinderX zonkTyVarBinderX :: ZonkEnv -> VarBndr TcTyVar vis -> TcM (ZonkEnv, VarBndr TyVar vis) -- Takes a TcTyVar and guarantees to return a TyVar zonkTyVarBinderX env (Bndr tv vis) = do { (env', tv') <- zonkTyBndrX env tv ; return (env', Bndr tv' vis) } zonkTopExpr :: HsExpr GhcTcId -> TcM (HsExpr GhcTc) zonkTopExpr e = initZonkEnv $ \ ze -> zonkExpr ze e zonkTopLExpr :: LHsExpr GhcTcId -> TcM (LHsExpr GhcTc) zonkTopLExpr e = initZonkEnv $ \ ze -> zonkLExpr ze e zonkTopDecls :: Bag EvBind -> LHsBinds GhcTcId -> [LRuleDecl GhcTcId] -> [LTcSpecPrag] -> [LForeignDecl GhcTcId] -> TcM (TypeEnv, Bag EvBind, LHsBinds GhcTc, [LForeignDecl GhcTc], [LTcSpecPrag], [LRuleDecl GhcTc]) zonkTopDecls ev_binds binds rules imp_specs fords = do { (env1, ev_binds') <- initZonkEnv $ \ ze -> zonkEvBinds ze ev_binds ; (env2, binds') <- zonkRecMonoBinds env1 binds -- Top level is implicitly recursive ; rules' <- zonkRules env2 rules ; specs' <- zonkLTcSpecPrags env2 imp_specs ; fords' <- zonkForeignExports env2 fords ; return (zonkEnvIds env2, ev_binds', binds', fords', specs', rules') } --------------------------------------------- zonkLocalBinds :: ZonkEnv -> HsLocalBinds GhcTcId -> TcM (ZonkEnv, HsLocalBinds GhcTc) zonkLocalBinds env (EmptyLocalBinds x) = return (env, (EmptyLocalBinds x)) zonkLocalBinds _ (HsValBinds _ (ValBinds {})) = panic "zonkLocalBinds" -- Not in typechecker output zonkLocalBinds env (HsValBinds x (XValBindsLR (NValBinds binds sigs))) = do { (env1, new_binds) <- go env binds ; return (env1, HsValBinds x (XValBindsLR (NValBinds new_binds sigs))) } where go env [] = return (env, []) go env ((r,b):bs) = do { (env1, b') <- zonkRecMonoBinds env b ; (env2, bs') <- go env1 bs ; return (env2, (r,b'):bs') } zonkLocalBinds env (HsIPBinds x (IPBinds dict_binds binds )) = do new_binds <- mapM (wrapLocM zonk_ip_bind) binds let env1 = extendIdZonkEnvRec env [ n | (dL->L _ (IPBind _ (Right n) _)) <- new_binds] (env2, new_dict_binds) <- zonkTcEvBinds env1 dict_binds return (env2, HsIPBinds x (IPBinds new_dict_binds new_binds)) where zonk_ip_bind (IPBind x n e) = do n' <- mapIPNameTc (zonkIdBndr env) n e' <- zonkLExpr env e return (IPBind x n' e') zonk_ip_bind (XIPBind nec) = noExtCon nec zonkLocalBinds _ (HsIPBinds _ (XHsIPBinds nec)) = noExtCon nec zonkLocalBinds _ (XHsLocalBindsLR nec) = noExtCon nec --------------------------------------------- zonkRecMonoBinds :: ZonkEnv -> LHsBinds GhcTcId -> TcM (ZonkEnv, LHsBinds GhcTc) zonkRecMonoBinds env binds = fixM (\ ~(_, new_binds) -> do { let env1 = extendIdZonkEnvRec env (collectHsBindsBinders new_binds) ; binds' <- zonkMonoBinds env1 binds ; return (env1, binds') }) --------------------------------------------- zonkMonoBinds :: ZonkEnv -> LHsBinds GhcTcId -> TcM (LHsBinds GhcTc) zonkMonoBinds env binds = mapBagM (zonk_lbind env) binds zonk_lbind :: ZonkEnv -> LHsBind GhcTcId -> TcM (LHsBind GhcTc) zonk_lbind env = wrapLocM (zonk_bind env) zonk_bind :: ZonkEnv -> HsBind GhcTcId -> TcM (HsBind GhcTc) zonk_bind env bind@(PatBind { pat_lhs = pat, pat_rhs = grhss , pat_ext = NPatBindTc fvs ty}) = do { (_env, new_pat) <- zonkPat env pat -- Env already extended ; new_grhss <- zonkGRHSs env zonkLExpr grhss ; new_ty <- zonkTcTypeToTypeX env ty ; return (bind { pat_lhs = new_pat, pat_rhs = new_grhss , pat_ext = NPatBindTc fvs new_ty }) } zonk_bind env (VarBind { var_ext = x , var_id = var, var_rhs = expr, var_inline = inl }) = do { new_var <- zonkIdBndr env var ; new_expr <- zonkLExpr env expr ; return (VarBind { var_ext = x , var_id = new_var , var_rhs = new_expr , var_inline = inl }) } zonk_bind env bind@(FunBind { fun_id = (dL->L loc var) , fun_matches = ms , fun_co_fn = co_fn }) = do { new_var <- zonkIdBndr env var ; (env1, new_co_fn) <- zonkCoFn env co_fn ; new_ms <- zonkMatchGroup env1 zonkLExpr ms ; return (bind { fun_id = cL loc new_var , fun_matches = new_ms , fun_co_fn = new_co_fn }) } zonk_bind env (AbsBinds { abs_tvs = tyvars, abs_ev_vars = evs , abs_ev_binds = ev_binds , abs_exports = exports , abs_binds = val_binds , abs_sig = has_sig }) = ASSERT( all isImmutableTyVar tyvars ) do { (env0, new_tyvars) <- zonkTyBndrsX env tyvars ; (env1, new_evs) <- zonkEvBndrsX env0 evs ; (env2, new_ev_binds) <- zonkTcEvBinds_s env1 ev_binds ; (new_val_bind, new_exports) <- fixM $ \ ~(new_val_binds, _) -> do { let env3 = extendIdZonkEnvRec env2 $ collectHsBindsBinders new_val_binds ; new_val_binds <- mapBagM (zonk_val_bind env3) val_binds ; new_exports <- mapM (zonk_export env3) exports ; return (new_val_binds, new_exports) } ; return (AbsBinds { abs_ext = noExtField , abs_tvs = new_tyvars, abs_ev_vars = new_evs , abs_ev_binds = new_ev_binds , abs_exports = new_exports, abs_binds = new_val_bind , abs_sig = has_sig }) } where zonk_val_bind env lbind | has_sig , (dL->L loc bind@(FunBind { fun_id = (dL->L mloc mono_id) , fun_matches = ms , fun_co_fn = co_fn })) <- lbind = do { new_mono_id <- updateVarTypeM (zonkTcTypeToTypeX env) mono_id -- Specifically /not/ zonkIdBndr; we do not -- want to complain about a levity-polymorphic binder ; (env', new_co_fn) <- zonkCoFn env co_fn ; new_ms <- zonkMatchGroup env' zonkLExpr ms ; return $ cL loc $ bind { fun_id = cL mloc new_mono_id , fun_matches = new_ms , fun_co_fn = new_co_fn } } | otherwise = zonk_lbind env lbind -- The normal case zonk_export env (ABE{ abe_ext = x , abe_wrap = wrap , abe_poly = poly_id , abe_mono = mono_id , abe_prags = prags }) = do new_poly_id <- zonkIdBndr env poly_id (_, new_wrap) <- zonkCoFn env wrap new_prags <- zonkSpecPrags env prags return (ABE{ abe_ext = x , abe_wrap = new_wrap , abe_poly = new_poly_id , abe_mono = zonkIdOcc env mono_id , abe_prags = new_prags }) zonk_export _ (XABExport nec) = noExtCon nec zonk_bind env (PatSynBind x bind@(PSB { psb_id = (dL->L loc id) , psb_args = details , psb_def = lpat , psb_dir = dir })) = do { id' <- zonkIdBndr env id ; (env1, lpat') <- zonkPat env lpat ; let details' = zonkPatSynDetails env1 details ; (_env2, dir') <- zonkPatSynDir env1 dir ; return $ PatSynBind x $ bind { psb_id = cL loc id' , psb_args = details' , psb_def = lpat' , psb_dir = dir' } } zonk_bind _ (PatSynBind _ (XPatSynBind nec)) = noExtCon nec zonk_bind _ (XHsBindsLR nec) = noExtCon nec zonkPatSynDetails :: ZonkEnv -> HsPatSynDetails (Located TcId) -> HsPatSynDetails (Located Id) zonkPatSynDetails env (PrefixCon as) = PrefixCon (map (zonkLIdOcc env) as) zonkPatSynDetails env (InfixCon a1 a2) = InfixCon (zonkLIdOcc env a1) (zonkLIdOcc env a2) zonkPatSynDetails env (RecCon flds) = RecCon (map (fmap (zonkLIdOcc env)) flds) zonkPatSynDir :: ZonkEnv -> HsPatSynDir GhcTcId -> TcM (ZonkEnv, HsPatSynDir GhcTc) zonkPatSynDir env Unidirectional = return (env, Unidirectional) zonkPatSynDir env ImplicitBidirectional = return (env, ImplicitBidirectional) zonkPatSynDir env (ExplicitBidirectional mg) = do mg' <- zonkMatchGroup env zonkLExpr mg return (env, ExplicitBidirectional mg') zonkSpecPrags :: ZonkEnv -> TcSpecPrags -> TcM TcSpecPrags zonkSpecPrags _ IsDefaultMethod = return IsDefaultMethod zonkSpecPrags env (SpecPrags ps) = do { ps' <- zonkLTcSpecPrags env ps ; return (SpecPrags ps') } zonkLTcSpecPrags :: ZonkEnv -> [LTcSpecPrag] -> TcM [LTcSpecPrag] zonkLTcSpecPrags env ps = mapM zonk_prag ps where zonk_prag (dL->L loc (SpecPrag id co_fn inl)) = do { (_, co_fn') <- zonkCoFn env co_fn ; return (cL loc (SpecPrag (zonkIdOcc env id) co_fn' inl)) } {- ************************************************************************ * * \subsection[BackSubst-Match-GRHSs]{Match and GRHSs} * * ************************************************************************ -} zonkMatchGroup :: ZonkEnv -> (ZonkEnv -> Located (body GhcTcId) -> TcM (Located (body GhcTc))) -> MatchGroup GhcTcId (Located (body GhcTcId)) -> TcM (MatchGroup GhcTc (Located (body GhcTc))) zonkMatchGroup env zBody (MG { mg_alts = (dL->L l ms) , mg_ext = MatchGroupTc arg_tys res_ty , mg_origin = origin }) = do { ms' <- mapM (zonkMatch env zBody) ms ; arg_tys' <- zonkTcTypesToTypesX env arg_tys ; res_ty' <- zonkTcTypeToTypeX env res_ty ; return (MG { mg_alts = cL l ms' , mg_ext = MatchGroupTc arg_tys' res_ty' , mg_origin = origin }) } zonkMatchGroup _ _ (XMatchGroup nec) = noExtCon nec zonkMatch :: ZonkEnv -> (ZonkEnv -> Located (body GhcTcId) -> TcM (Located (body GhcTc))) -> LMatch GhcTcId (Located (body GhcTcId)) -> TcM (LMatch GhcTc (Located (body GhcTc))) zonkMatch env zBody (dL->L loc match@(Match { m_pats = pats , m_grhss = grhss })) = do { (env1, new_pats) <- zonkPats env pats ; new_grhss <- zonkGRHSs env1 zBody grhss ; return (cL loc (match { m_pats = new_pats, m_grhss = new_grhss })) } zonkMatch _ _ (dL->L _ (XMatch nec)) = noExtCon nec zonkMatch _ _ _ = panic "zonkMatch: Impossible Match" -- due to #15884 ------------------------------------------------------------------------- zonkGRHSs :: ZonkEnv -> (ZonkEnv -> Located (body GhcTcId) -> TcM (Located (body GhcTc))) -> GRHSs GhcTcId (Located (body GhcTcId)) -> TcM (GRHSs GhcTc (Located (body GhcTc))) zonkGRHSs env zBody (GRHSs x grhss (dL->L l binds)) = do (new_env, new_binds) <- zonkLocalBinds env binds let zonk_grhs (GRHS xx guarded rhs) = do (env2, new_guarded) <- zonkStmts new_env zonkLExpr guarded new_rhs <- zBody env2 rhs return (GRHS xx new_guarded new_rhs) zonk_grhs (XGRHS nec) = noExtCon nec new_grhss <- mapM (wrapLocM zonk_grhs) grhss return (GRHSs x new_grhss (cL l new_binds)) zonkGRHSs _ _ (XGRHSs nec) = noExtCon nec {- ************************************************************************ * * \subsection[BackSubst-HsExpr]{Running a zonkitution over a TypeCheckedExpr} * * ************************************************************************ -} zonkLExprs :: ZonkEnv -> [LHsExpr GhcTcId] -> TcM [LHsExpr GhcTc] zonkLExpr :: ZonkEnv -> LHsExpr GhcTcId -> TcM (LHsExpr GhcTc) zonkExpr :: ZonkEnv -> HsExpr GhcTcId -> TcM (HsExpr GhcTc) zonkLExprs env exprs = mapM (zonkLExpr env) exprs zonkLExpr env expr = wrapLocM (zonkExpr env) expr zonkExpr env (HsVar x (dL->L l id)) = ASSERT2( isNothing (isDataConId_maybe id), ppr id ) return (HsVar x (cL l (zonkIdOcc env id))) zonkExpr _ e@(HsConLikeOut {}) = return e zonkExpr _ (HsIPVar x id) = return (HsIPVar x id) zonkExpr _ e@HsOverLabel{} = return e zonkExpr env (HsLit x (HsRat e f ty)) = do new_ty <- zonkTcTypeToTypeX env ty return (HsLit x (HsRat e f new_ty)) zonkExpr _ (HsLit x lit) = return (HsLit x lit) zonkExpr env (HsOverLit x lit) = do { lit' <- zonkOverLit env lit ; return (HsOverLit x lit') } zonkExpr env (HsLam x matches) = do new_matches <- zonkMatchGroup env zonkLExpr matches return (HsLam x new_matches) zonkExpr env (HsLamCase x matches) = do new_matches <- zonkMatchGroup env zonkLExpr matches return (HsLamCase x new_matches) zonkExpr env (HsApp x e1 e2) = do new_e1 <- zonkLExpr env e1 new_e2 <- zonkLExpr env e2 return (HsApp x new_e1 new_e2) zonkExpr env (HsAppType x e t) = do new_e <- zonkLExpr env e return (HsAppType x new_e t) -- NB: the type is an HsType; can't zonk that! zonkExpr _ e@(HsRnBracketOut _ _ _) = pprPanic "zonkExpr: HsRnBracketOut" (ppr e) zonkExpr env (HsTcBracketOut x body bs) = do bs' <- mapM zonk_b bs return (HsTcBracketOut x body bs') where zonk_b (PendingTcSplice n e) = do e' <- zonkLExpr env e return (PendingTcSplice n e') zonkExpr env (HsSpliceE _ (HsSplicedT s)) = runTopSplice s >>= zonkExpr env zonkExpr _ (HsSpliceE x s) = WARN( True, ppr s ) -- Should not happen return (HsSpliceE x s) zonkExpr env (OpApp fixity e1 op e2) = do new_e1 <- zonkLExpr env e1 new_op <- zonkLExpr env op new_e2 <- zonkLExpr env e2 return (OpApp fixity new_e1 new_op new_e2) zonkExpr env (NegApp x expr op) = do (env', new_op) <- zonkSyntaxExpr env op new_expr <- zonkLExpr env' expr return (NegApp x new_expr new_op) zonkExpr env (HsPar x e) = do new_e <- zonkLExpr env e return (HsPar x new_e) zonkExpr env (SectionL x expr op) = do new_expr <- zonkLExpr env expr new_op <- zonkLExpr env op return (SectionL x new_expr new_op) zonkExpr env (SectionR x op expr) = do new_op <- zonkLExpr env op new_expr <- zonkLExpr env expr return (SectionR x new_op new_expr) zonkExpr env (ExplicitTuple x tup_args boxed) = do { new_tup_args <- mapM zonk_tup_arg tup_args ; return (ExplicitTuple x new_tup_args boxed) } where zonk_tup_arg (dL->L l (Present x e)) = do { e' <- zonkLExpr env e ; return (cL l (Present x e')) } zonk_tup_arg (dL->L l (Missing t)) = do { t' <- zonkTcTypeToTypeX env t ; return (cL l (Missing t')) } zonk_tup_arg (dL->L _ (XTupArg nec)) = noExtCon nec zonk_tup_arg _ = panic "zonk_tup_arg: Impossible Match" -- due to #15884 zonkExpr env (ExplicitSum args alt arity expr) = do new_args <- mapM (zonkTcTypeToTypeX env) args new_expr <- zonkLExpr env expr return (ExplicitSum new_args alt arity new_expr) zonkExpr env (HsCase x expr ms) = do new_expr <- zonkLExpr env expr new_ms <- zonkMatchGroup env zonkLExpr ms return (HsCase x new_expr new_ms) zonkExpr env (HsIf x Nothing e1 e2 e3) = do new_e1 <- zonkLExpr env e1 new_e2 <- zonkLExpr env e2 new_e3 <- zonkLExpr env e3 return (HsIf x Nothing new_e1 new_e2 new_e3) zonkExpr env (HsIf x (Just fun) e1 e2 e3) = do (env1, new_fun) <- zonkSyntaxExpr env fun new_e1 <- zonkLExpr env1 e1 new_e2 <- zonkLExpr env1 e2 new_e3 <- zonkLExpr env1 e3 return (HsIf x (Just new_fun) new_e1 new_e2 new_e3) zonkExpr env (HsMultiIf ty alts) = do { alts' <- mapM (wrapLocM zonk_alt) alts ; ty' <- zonkTcTypeToTypeX env ty ; return $ HsMultiIf ty' alts' } where zonk_alt (GRHS x guard expr) = do { (env', guard') <- zonkStmts env zonkLExpr guard ; expr' <- zonkLExpr env' expr ; return $ GRHS x guard' expr' } zonk_alt (XGRHS nec) = noExtCon nec zonkExpr env (HsLet x (dL->L l binds) expr) = do (new_env, new_binds) <- zonkLocalBinds env binds new_expr <- zonkLExpr new_env expr return (HsLet x (cL l new_binds) new_expr) zonkExpr env (HsDo ty do_or_lc (dL->L l stmts)) = do (_, new_stmts) <- zonkStmts env zonkLExpr stmts new_ty <- zonkTcTypeToTypeX env ty return (HsDo new_ty do_or_lc (cL l new_stmts)) zonkExpr env (ExplicitList ty wit exprs) = do (env1, new_wit) <- zonkWit env wit new_ty <- zonkTcTypeToTypeX env1 ty new_exprs <- zonkLExprs env1 exprs return (ExplicitList new_ty new_wit new_exprs) where zonkWit env Nothing = return (env, Nothing) zonkWit env (Just fln) = second Just <$> zonkSyntaxExpr env fln zonkExpr env expr@(RecordCon { rcon_ext = ext, rcon_flds = rbinds }) = do { new_con_expr <- zonkExpr env (rcon_con_expr ext) ; new_rbinds <- zonkRecFields env rbinds ; return (expr { rcon_ext = ext { rcon_con_expr = new_con_expr } , rcon_flds = new_rbinds }) } zonkExpr env (RecordUpd { rupd_flds = rbinds , rupd_expr = expr , rupd_ext = RecordUpdTc { rupd_cons = cons, rupd_in_tys = in_tys , rupd_out_tys = out_tys, rupd_wrap = req_wrap }}) = do { new_expr <- zonkLExpr env expr ; new_in_tys <- mapM (zonkTcTypeToTypeX env) in_tys ; new_out_tys <- mapM (zonkTcTypeToTypeX env) out_tys ; new_rbinds <- zonkRecUpdFields env rbinds ; (_, new_recwrap) <- zonkCoFn env req_wrap ; return (RecordUpd { rupd_expr = new_expr, rupd_flds = new_rbinds , rupd_ext = RecordUpdTc { rupd_cons = cons, rupd_in_tys = new_in_tys , rupd_out_tys = new_out_tys , rupd_wrap = new_recwrap }}) } zonkExpr env (ExprWithTySig _ e ty) = do { e' <- zonkLExpr env e ; return (ExprWithTySig noExtField e' ty) } zonkExpr env (ArithSeq expr wit info) = do (env1, new_wit) <- zonkWit env wit new_expr <- zonkExpr env expr new_info <- zonkArithSeq env1 info return (ArithSeq new_expr new_wit new_info) where zonkWit env Nothing = return (env, Nothing) zonkWit env (Just fln) = second Just <$> zonkSyntaxExpr env fln zonkExpr env (HsSCC x src lbl expr) = do new_expr <- zonkLExpr env expr return (HsSCC x src lbl new_expr) zonkExpr env (HsTickPragma x src info srcInfo expr) = do new_expr <- zonkLExpr env expr return (HsTickPragma x src info srcInfo new_expr) -- hdaume: core annotations zonkExpr env (HsCoreAnn x src lbl expr) = do new_expr <- zonkLExpr env expr return (HsCoreAnn x src lbl new_expr) -- arrow notation extensions zonkExpr env (HsProc x pat body) = do { (env1, new_pat) <- zonkPat env pat ; new_body <- zonkCmdTop env1 body ; return (HsProc x new_pat new_body) } -- StaticPointers extension zonkExpr env (HsStatic fvs expr) = HsStatic fvs <$> zonkLExpr env expr zonkExpr env (HsWrap x co_fn expr) = do (env1, new_co_fn) <- zonkCoFn env co_fn new_expr <- zonkExpr env1 expr return (HsWrap x new_co_fn new_expr) zonkExpr _ e@(HsUnboundVar {}) = return e zonkExpr _ expr = pprPanic "zonkExpr" (ppr expr) ------------------------------------------------------------------------- {- Note [Skolems in zonkSyntaxExpr] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Consider rebindable syntax with something like (>>=) :: (forall x. blah) -> (forall y. blah') -> blah'' The x and y become skolems that are in scope when type-checking the arguments to the bind. This means that we must extend the ZonkEnv with these skolems when zonking the arguments to the bind. But the skolems are different between the two arguments, and so we should theoretically carry around different environments to use for the different arguments. However, this becomes a logistical nightmare, especially in dealing with the more exotic Stmt forms. So, we simplify by making the critical assumption that the uniques of the skolems are different. (This assumption is justified by the use of newUnique in TcMType.instSkolTyCoVarX.) Now, we can safely just extend one environment. -} -- See Note [Skolems in zonkSyntaxExpr] zonkSyntaxExpr :: ZonkEnv -> SyntaxExpr GhcTcId -> TcM (ZonkEnv, SyntaxExpr GhcTc) zonkSyntaxExpr env (SyntaxExpr { syn_expr = expr , syn_arg_wraps = arg_wraps , syn_res_wrap = res_wrap }) = do { (env0, res_wrap') <- zonkCoFn env res_wrap ; expr' <- zonkExpr env0 expr ; (env1, arg_wraps') <- mapAccumLM zonkCoFn env0 arg_wraps ; return (env1, SyntaxExpr { syn_expr = expr' , syn_arg_wraps = arg_wraps' , syn_res_wrap = res_wrap' }) } ------------------------------------------------------------------------- zonkLCmd :: ZonkEnv -> LHsCmd GhcTcId -> TcM (LHsCmd GhcTc) zonkCmd :: ZonkEnv -> HsCmd GhcTcId -> TcM (HsCmd GhcTc) zonkLCmd env cmd = wrapLocM (zonkCmd env) cmd zonkCmd env (HsCmdWrap x w cmd) = do { (env1, w') <- zonkCoFn env w ; cmd' <- zonkCmd env1 cmd ; return (HsCmdWrap x w' cmd') } zonkCmd env (HsCmdArrApp ty e1 e2 ho rl) = do new_e1 <- zonkLExpr env e1 new_e2 <- zonkLExpr env e2 new_ty <- zonkTcTypeToTypeX env ty return (HsCmdArrApp new_ty new_e1 new_e2 ho rl) zonkCmd env (HsCmdArrForm x op f fixity args) = do new_op <- zonkLExpr env op new_args <- mapM (zonkCmdTop env) args return (HsCmdArrForm x new_op f fixity new_args) zonkCmd env (HsCmdApp x c e) = do new_c <- zonkLCmd env c new_e <- zonkLExpr env e return (HsCmdApp x new_c new_e) zonkCmd env (HsCmdLam x matches) = do new_matches <- zonkMatchGroup env zonkLCmd matches return (HsCmdLam x new_matches) zonkCmd env (HsCmdPar x c) = do new_c <- zonkLCmd env c return (HsCmdPar x new_c) zonkCmd env (HsCmdCase x expr ms) = do new_expr <- zonkLExpr env expr new_ms <- zonkMatchGroup env zonkLCmd ms return (HsCmdCase x new_expr new_ms) zonkCmd env (HsCmdIf x eCond ePred cThen cElse) = do { (env1, new_eCond) <- zonkWit env eCond ; new_ePred <- zonkLExpr env1 ePred ; new_cThen <- zonkLCmd env1 cThen ; new_cElse <- zonkLCmd env1 cElse ; return (HsCmdIf x new_eCond new_ePred new_cThen new_cElse) } where zonkWit env Nothing = return (env, Nothing) zonkWit env (Just w) = second Just <$> zonkSyntaxExpr env w zonkCmd env (HsCmdLet x (dL->L l binds) cmd) = do (new_env, new_binds) <- zonkLocalBinds env binds new_cmd <- zonkLCmd new_env cmd return (HsCmdLet x (cL l new_binds) new_cmd) zonkCmd env (HsCmdDo ty (dL->L l stmts)) = do (_, new_stmts) <- zonkStmts env zonkLCmd stmts new_ty <- zonkTcTypeToTypeX env ty return (HsCmdDo new_ty (cL l new_stmts)) zonkCmd _ (XCmd nec) = noExtCon nec zonkCmdTop :: ZonkEnv -> LHsCmdTop GhcTcId -> TcM (LHsCmdTop GhcTc) zonkCmdTop env cmd = wrapLocM (zonk_cmd_top env) cmd zonk_cmd_top :: ZonkEnv -> HsCmdTop GhcTcId -> TcM (HsCmdTop GhcTc) zonk_cmd_top env (HsCmdTop (CmdTopTc stack_tys ty ids) cmd) = do new_cmd <- zonkLCmd env cmd new_stack_tys <- zonkTcTypeToTypeX env stack_tys new_ty <- zonkTcTypeToTypeX env ty new_ids <- mapSndM (zonkExpr env) ids MASSERT( isLiftedTypeKind (tcTypeKind new_stack_tys) ) -- desugarer assumes that this is not levity polymorphic... -- but indeed it should always be lifted due to the typing -- rules for arrows return (HsCmdTop (CmdTopTc new_stack_tys new_ty new_ids) new_cmd) zonk_cmd_top _ (XCmdTop nec) = noExtCon nec ------------------------------------------------------------------------- zonkCoFn :: ZonkEnv -> HsWrapper -> TcM (ZonkEnv, HsWrapper) zonkCoFn env WpHole = return (env, WpHole) zonkCoFn env (WpCompose c1 c2) = do { (env1, c1') <- zonkCoFn env c1 ; (env2, c2') <- zonkCoFn env1 c2 ; return (env2, WpCompose c1' c2') } zonkCoFn env (WpFun c1 c2 t1 d) = do { (env1, c1') <- zonkCoFn env c1 ; (env2, c2') <- zonkCoFn env1 c2 ; t1' <- zonkTcTypeToTypeX env2 t1 ; return (env2, WpFun c1' c2' t1' d) } zonkCoFn env (WpCast co) = do { co' <- zonkCoToCo env co ; return (env, WpCast co') } zonkCoFn env (WpEvLam ev) = do { (env', ev') <- zonkEvBndrX env ev ; return (env', WpEvLam ev') } zonkCoFn env (WpEvApp arg) = do { arg' <- zonkEvTerm env arg ; return (env, WpEvApp arg') } zonkCoFn env (WpTyLam tv) = ASSERT( isImmutableTyVar tv ) do { (env', tv') <- zonkTyBndrX env tv ; return (env', WpTyLam tv') } zonkCoFn env (WpTyApp ty) = do { ty' <- zonkTcTypeToTypeX env ty ; return (env, WpTyApp ty') } zonkCoFn env (WpLet bs) = do { (env1, bs') <- zonkTcEvBinds env bs ; return (env1, WpLet bs') } ------------------------------------------------------------------------- zonkOverLit :: ZonkEnv -> HsOverLit GhcTcId -> TcM (HsOverLit GhcTc) zonkOverLit env lit@(OverLit {ol_ext = OverLitTc r ty, ol_witness = e }) = do { ty' <- zonkTcTypeToTypeX env ty ; e' <- zonkExpr env e ; return (lit { ol_witness = e', ol_ext = OverLitTc r ty' }) } zonkOverLit _ (XOverLit nec) = noExtCon nec ------------------------------------------------------------------------- zonkArithSeq :: ZonkEnv -> ArithSeqInfo GhcTcId -> TcM (ArithSeqInfo GhcTc) zonkArithSeq env (From e) = do new_e <- zonkLExpr env e return (From new_e) zonkArithSeq env (FromThen e1 e2) = do new_e1 <- zonkLExpr env e1 new_e2 <- zonkLExpr env e2 return (FromThen new_e1 new_e2) zonkArithSeq env (FromTo e1 e2) = do new_e1 <- zonkLExpr env e1 new_e2 <- zonkLExpr env e2 return (FromTo new_e1 new_e2) zonkArithSeq env (FromThenTo e1 e2 e3) = do new_e1 <- zonkLExpr env e1 new_e2 <- zonkLExpr env e2 new_e3 <- zonkLExpr env e3 return (FromThenTo new_e1 new_e2 new_e3) ------------------------------------------------------------------------- zonkStmts :: ZonkEnv -> (ZonkEnv -> Located (body GhcTcId) -> TcM (Located (body GhcTc))) -> [LStmt GhcTcId (Located (body GhcTcId))] -> TcM (ZonkEnv, [LStmt GhcTc (Located (body GhcTc))]) zonkStmts env _ [] = return (env, []) zonkStmts env zBody (s:ss) = do { (env1, s') <- wrapLocSndM (zonkStmt env zBody) s ; (env2, ss') <- zonkStmts env1 zBody ss ; return (env2, s' : ss') } zonkStmt :: ZonkEnv -> (ZonkEnv -> Located (body GhcTcId) -> TcM (Located (body GhcTc))) -> Stmt GhcTcId (Located (body GhcTcId)) -> TcM (ZonkEnv, Stmt GhcTc (Located (body GhcTc))) zonkStmt env _ (ParStmt bind_ty stmts_w_bndrs mzip_op bind_op) = do { (env1, new_bind_op) <- zonkSyntaxExpr env bind_op ; new_bind_ty <- zonkTcTypeToTypeX env1 bind_ty ; new_stmts_w_bndrs <- mapM (zonk_branch env1) stmts_w_bndrs ; let new_binders = [b | ParStmtBlock _ _ bs _ <- new_stmts_w_bndrs , b <- bs] env2 = extendIdZonkEnvRec env1 new_binders ; new_mzip <- zonkExpr env2 mzip_op ; return (env2 , ParStmt new_bind_ty new_stmts_w_bndrs new_mzip new_bind_op)} where zonk_branch env1 (ParStmtBlock x stmts bndrs return_op) = do { (env2, new_stmts) <- zonkStmts env1 zonkLExpr stmts ; (env3, new_return) <- zonkSyntaxExpr env2 return_op ; return (ParStmtBlock x new_stmts (zonkIdOccs env3 bndrs) new_return) } zonk_branch _ (XParStmtBlock nec) = noExtCon nec zonkStmt env zBody (RecStmt { recS_stmts = segStmts, recS_later_ids = lvs, recS_rec_ids = rvs , recS_ret_fn = ret_id, recS_mfix_fn = mfix_id , recS_bind_fn = bind_id , recS_ext = RecStmtTc { recS_bind_ty = bind_ty , recS_later_rets = later_rets , recS_rec_rets = rec_rets , recS_ret_ty = ret_ty} }) = do { (env1, new_bind_id) <- zonkSyntaxExpr env bind_id ; (env2, new_mfix_id) <- zonkSyntaxExpr env1 mfix_id ; (env3, new_ret_id) <- zonkSyntaxExpr env2 ret_id ; new_bind_ty <- zonkTcTypeToTypeX env3 bind_ty ; new_rvs <- zonkIdBndrs env3 rvs ; new_lvs <- zonkIdBndrs env3 lvs ; new_ret_ty <- zonkTcTypeToTypeX env3 ret_ty ; let env4 = extendIdZonkEnvRec env3 new_rvs ; (env5, new_segStmts) <- zonkStmts env4 zBody segStmts -- Zonk the ret-expressions in an envt that -- has the polymorphic bindings in the envt ; new_later_rets <- mapM (zonkExpr env5) later_rets ; new_rec_rets <- mapM (zonkExpr env5) rec_rets ; return (extendIdZonkEnvRec env3 new_lvs, -- Only the lvs are needed RecStmt { recS_stmts = new_segStmts, recS_later_ids = new_lvs , recS_rec_ids = new_rvs, recS_ret_fn = new_ret_id , recS_mfix_fn = new_mfix_id, recS_bind_fn = new_bind_id , recS_ext = RecStmtTc { recS_bind_ty = new_bind_ty , recS_later_rets = new_later_rets , recS_rec_rets = new_rec_rets , recS_ret_ty = new_ret_ty } }) } zonkStmt env zBody (BodyStmt ty body then_op guard_op) = do (env1, new_then_op) <- zonkSyntaxExpr env then_op (env2, new_guard_op) <- zonkSyntaxExpr env1 guard_op new_body <- zBody env2 body new_ty <- zonkTcTypeToTypeX env2 ty return (env2, BodyStmt new_ty new_body new_then_op new_guard_op) zonkStmt env zBody (LastStmt x body noret ret_op) = do (env1, new_ret) <- zonkSyntaxExpr env ret_op new_body <- zBody env1 body return (env, LastStmt x new_body noret new_ret) zonkStmt env _ (TransStmt { trS_stmts = stmts, trS_bndrs = binderMap , trS_by = by, trS_form = form, trS_using = using , trS_ret = return_op, trS_bind = bind_op , trS_ext = bind_arg_ty , trS_fmap = liftM_op }) = do { ; (env1, bind_op') <- zonkSyntaxExpr env bind_op ; bind_arg_ty' <- zonkTcTypeToTypeX env1 bind_arg_ty ; (env2, stmts') <- zonkStmts env1 zonkLExpr stmts ; by' <- fmapMaybeM (zonkLExpr env2) by ; using' <- zonkLExpr env2 using ; (env3, return_op') <- zonkSyntaxExpr env2 return_op ; binderMap' <- mapM (zonkBinderMapEntry env3) binderMap ; liftM_op' <- zonkExpr env3 liftM_op ; let env3' = extendIdZonkEnvRec env3 (map snd binderMap') ; return (env3', TransStmt { trS_stmts = stmts', trS_bndrs = binderMap' , trS_by = by', trS_form = form, trS_using = using' , trS_ret = return_op', trS_bind = bind_op' , trS_ext = bind_arg_ty' , trS_fmap = liftM_op' }) } where zonkBinderMapEntry env (oldBinder, newBinder) = do let oldBinder' = zonkIdOcc env oldBinder newBinder' <- zonkIdBndr env newBinder return (oldBinder', newBinder') zonkStmt env _ (LetStmt x (dL->L l binds)) = do (env1, new_binds) <- zonkLocalBinds env binds return (env1, LetStmt x (cL l new_binds)) zonkStmt env zBody (BindStmt bind_ty pat body bind_op fail_op) = do { (env1, new_bind) <- zonkSyntaxExpr env bind_op ; new_bind_ty <- zonkTcTypeToTypeX env1 bind_ty ; new_body <- zBody env1 body ; (env2, new_pat) <- zonkPat env1 pat ; (_, new_fail) <- zonkSyntaxExpr env1 fail_op ; return ( env2 , BindStmt new_bind_ty new_pat new_body new_bind new_fail) } -- Scopes: join > ops (in reverse order) > pats (in forward order) -- > rest of stmts zonkStmt env _zBody (ApplicativeStmt body_ty args mb_join) = do { (env1, new_mb_join) <- zonk_join env mb_join ; (env2, new_args) <- zonk_args env1 args ; new_body_ty <- zonkTcTypeToTypeX env2 body_ty ; return ( env2 , ApplicativeStmt new_body_ty new_args new_mb_join) } where zonk_join env Nothing = return (env, Nothing) zonk_join env (Just j) = second Just <$> zonkSyntaxExpr env j get_pat (_, ApplicativeArgOne _ pat _ _ _) = pat get_pat (_, ApplicativeArgMany _ _ _ pat) = pat get_pat (_, XApplicativeArg nec) = noExtCon nec replace_pat pat (op, ApplicativeArgOne x _ a isBody fail_op) = (op, ApplicativeArgOne x pat a isBody fail_op) replace_pat pat (op, ApplicativeArgMany x a b _) = (op, ApplicativeArgMany x a b pat) replace_pat _ (_, XApplicativeArg nec) = noExtCon nec zonk_args env args = do { (env1, new_args_rev) <- zonk_args_rev env (reverse args) ; (env2, new_pats) <- zonkPats env1 (map get_pat args) ; return (env2, zipWith replace_pat new_pats (reverse new_args_rev)) } -- these need to go backward, because if any operators are higher-rank, -- later operators may introduce skolems that are in scope for earlier -- arguments zonk_args_rev env ((op, arg) : args) = do { (env1, new_op) <- zonkSyntaxExpr env op ; new_arg <- zonk_arg env1 arg ; (env2, new_args) <- zonk_args_rev env1 args ; return (env2, (new_op, new_arg) : new_args) } zonk_args_rev env [] = return (env, []) zonk_arg env (ApplicativeArgOne x pat expr isBody fail_op) = do { new_expr <- zonkLExpr env expr ; (_, new_fail) <- zonkSyntaxExpr env fail_op ; return (ApplicativeArgOne x pat new_expr isBody new_fail) } zonk_arg env (ApplicativeArgMany x stmts ret pat) = do { (env1, new_stmts) <- zonkStmts env zonkLExpr stmts ; new_ret <- zonkExpr env1 ret ; return (ApplicativeArgMany x new_stmts new_ret pat) } zonk_arg _ (XApplicativeArg nec) = noExtCon nec zonkStmt _ _ (XStmtLR nec) = noExtCon nec ------------------------------------------------------------------------- zonkRecFields :: ZonkEnv -> HsRecordBinds GhcTcId -> TcM (HsRecordBinds GhcTcId) zonkRecFields env (HsRecFields flds dd) = do { flds' <- mapM zonk_rbind flds ; return (HsRecFields flds' dd) } where zonk_rbind (dL->L l fld) = do { new_id <- wrapLocM (zonkFieldOcc env) (hsRecFieldLbl fld) ; new_expr <- zonkLExpr env (hsRecFieldArg fld) ; return (cL l (fld { hsRecFieldLbl = new_id , hsRecFieldArg = new_expr })) } zonkRecUpdFields :: ZonkEnv -> [LHsRecUpdField GhcTcId] -> TcM [LHsRecUpdField GhcTcId] zonkRecUpdFields env = mapM zonk_rbind where zonk_rbind (dL->L l fld) = do { new_id <- wrapLocM (zonkFieldOcc env) (hsRecUpdFieldOcc fld) ; new_expr <- zonkLExpr env (hsRecFieldArg fld) ; return (cL l (fld { hsRecFieldLbl = fmap ambiguousFieldOcc new_id , hsRecFieldArg = new_expr })) } ------------------------------------------------------------------------- mapIPNameTc :: (a -> TcM b) -> Either (Located HsIPName) a -> TcM (Either (Located HsIPName) b) mapIPNameTc _ (Left x) = return (Left x) mapIPNameTc f (Right x) = do r <- f x return (Right r) {- ************************************************************************ * * \subsection[BackSubst-Pats]{Patterns} * * ************************************************************************ -} zonkPat :: ZonkEnv -> OutPat GhcTcId -> TcM (ZonkEnv, OutPat GhcTc) -- Extend the environment as we go, because it's possible for one -- pattern to bind something that is used in another (inside or -- to the right) zonkPat env pat = wrapLocSndM (zonk_pat env) pat zonk_pat :: ZonkEnv -> Pat GhcTcId -> TcM (ZonkEnv, Pat GhcTc) zonk_pat env (ParPat x p) = do { (env', p') <- zonkPat env p ; return (env', ParPat x p') } zonk_pat env (WildPat ty) = do { ty' <- zonkTcTypeToTypeX env ty ; ensureNotLevPoly ty' (text "In a wildcard pattern") ; return (env, WildPat ty') } zonk_pat env (VarPat x (dL->L l v)) = do { v' <- zonkIdBndr env v ; return (extendIdZonkEnv env v', VarPat x (cL l v')) } zonk_pat env (LazyPat x pat) = do { (env', pat') <- zonkPat env pat ; return (env', LazyPat x pat') } zonk_pat env (BangPat x pat) = do { (env', pat') <- zonkPat env pat ; return (env', BangPat x pat') } zonk_pat env (AsPat x (dL->L loc v) pat) = do { v' <- zonkIdBndr env v ; (env', pat') <- zonkPat (extendIdZonkEnv env v') pat ; return (env', AsPat x (cL loc v') pat') } zonk_pat env (ViewPat ty expr pat) = do { expr' <- zonkLExpr env expr ; (env', pat') <- zonkPat env pat ; ty' <- zonkTcTypeToTypeX env ty ; return (env', ViewPat ty' expr' pat') } zonk_pat env (ListPat (ListPatTc ty Nothing) pats) = do { ty' <- zonkTcTypeToTypeX env ty ; (env', pats') <- zonkPats env pats ; return (env', ListPat (ListPatTc ty' Nothing) pats') } zonk_pat env (ListPat (ListPatTc ty (Just (ty2,wit))) pats) = do { (env', wit') <- zonkSyntaxExpr env wit ; ty2' <- zonkTcTypeToTypeX env' ty2 ; ty' <- zonkTcTypeToTypeX env' ty ; (env'', pats') <- zonkPats env' pats ; return (env'', ListPat (ListPatTc ty' (Just (ty2',wit'))) pats') } zonk_pat env (TuplePat tys pats boxed) = do { tys' <- mapM (zonkTcTypeToTypeX env) tys ; (env', pats') <- zonkPats env pats ; return (env', TuplePat tys' pats' boxed) } zonk_pat env (SumPat tys pat alt arity ) = do { tys' <- mapM (zonkTcTypeToTypeX env) tys ; (env', pat') <- zonkPat env pat ; return (env', SumPat tys' pat' alt arity) } zonk_pat env p@(ConPatOut { pat_arg_tys = tys , pat_tvs = tyvars , pat_dicts = evs , pat_binds = binds , pat_args = args , pat_wrap = wrapper , pat_con = (dL->L _ con) }) = ASSERT( all isImmutableTyVar tyvars ) do { new_tys <- mapM (zonkTcTypeToTypeX env) tys -- an unboxed tuple pattern (but only an unboxed tuple pattern) -- might have levity-polymorphic arguments. Check for this badness. ; case con of RealDataCon dc | isUnboxedTupleTyCon (dataConTyCon dc) -> mapM_ (checkForLevPoly doc) (dropRuntimeRepArgs new_tys) _ -> return () ; (env0, new_tyvars) <- zonkTyBndrsX env tyvars -- Must zonk the existential variables, because their -- /kind/ need potential zonking. -- cf typecheck/should_compile/tc221.hs ; (env1, new_evs) <- zonkEvBndrsX env0 evs ; (env2, new_binds) <- zonkTcEvBinds env1 binds ; (env3, new_wrapper) <- zonkCoFn env2 wrapper ; (env', new_args) <- zonkConStuff env3 args ; return (env', p { pat_arg_tys = new_tys, pat_tvs = new_tyvars, pat_dicts = new_evs, pat_binds = new_binds, pat_args = new_args, pat_wrap = new_wrapper}) } where doc = text "In the type of an element of an unboxed tuple pattern:" $$ ppr p zonk_pat env (LitPat x lit) = return (env, LitPat x lit) zonk_pat env (SigPat ty pat hs_ty) = do { ty' <- zonkTcTypeToTypeX env ty ; (env', pat') <- zonkPat env pat ; return (env', SigPat ty' pat' hs_ty) } zonk_pat env (NPat ty (dL->L l lit) mb_neg eq_expr) = do { (env1, eq_expr') <- zonkSyntaxExpr env eq_expr ; (env2, mb_neg') <- case mb_neg of Nothing -> return (env1, Nothing) Just n -> second Just <$> zonkSyntaxExpr env1 n ; lit' <- zonkOverLit env2 lit ; ty' <- zonkTcTypeToTypeX env2 ty ; return (env2, NPat ty' (cL l lit') mb_neg' eq_expr') } zonk_pat env (NPlusKPat ty (dL->L loc n) (dL->L l lit1) lit2 e1 e2) = do { (env1, e1') <- zonkSyntaxExpr env e1 ; (env2, e2') <- zonkSyntaxExpr env1 e2 ; n' <- zonkIdBndr env2 n ; lit1' <- zonkOverLit env2 lit1 ; lit2' <- zonkOverLit env2 lit2 ; ty' <- zonkTcTypeToTypeX env2 ty ; return (extendIdZonkEnv env2 n', NPlusKPat ty' (cL loc n') (cL l lit1') lit2' e1' e2') } zonk_pat env (CoPat x co_fn pat ty) = do { (env', co_fn') <- zonkCoFn env co_fn ; (env'', pat') <- zonkPat env' (noLoc pat) ; ty' <- zonkTcTypeToTypeX env'' ty ; return (env'', CoPat x co_fn' (unLoc pat') ty') } zonk_pat _ pat = pprPanic "zonk_pat" (ppr pat) --------------------------- zonkConStuff :: ZonkEnv -> HsConDetails (OutPat GhcTcId) (HsRecFields id (OutPat GhcTcId)) -> TcM (ZonkEnv, HsConDetails (OutPat GhcTc) (HsRecFields id (OutPat GhcTc))) zonkConStuff env (PrefixCon pats) = do { (env', pats') <- zonkPats env pats ; return (env', PrefixCon pats') } zonkConStuff env (InfixCon p1 p2) = do { (env1, p1') <- zonkPat env p1 ; (env', p2') <- zonkPat env1 p2 ; return (env', InfixCon p1' p2') } zonkConStuff env (RecCon (HsRecFields rpats dd)) = do { (env', pats') <- zonkPats env (map (hsRecFieldArg . unLoc) rpats) ; let rpats' = zipWith (\(dL->L l rp) p' -> cL l (rp { hsRecFieldArg = p' })) rpats pats' ; return (env', RecCon (HsRecFields rpats' dd)) } -- Field selectors have declared types; hence no zonking --------------------------- zonkPats :: ZonkEnv -> [OutPat GhcTcId] -> TcM (ZonkEnv, [OutPat GhcTc]) zonkPats env [] = return (env, []) zonkPats env (pat:pats) = do { (env1, pat') <- zonkPat env pat ; (env', pats') <- zonkPats env1 pats ; return (env', pat':pats') } {- ************************************************************************ * * \subsection[BackSubst-Foreign]{Foreign exports} * * ************************************************************************ -} zonkForeignExports :: ZonkEnv -> [LForeignDecl GhcTcId] -> TcM [LForeignDecl GhcTc] zonkForeignExports env ls = mapM (wrapLocM (zonkForeignExport env)) ls zonkForeignExport :: ZonkEnv -> ForeignDecl GhcTcId -> TcM (ForeignDecl GhcTc) zonkForeignExport env (ForeignExport { fd_name = i, fd_e_ext = co , fd_fe = spec }) = return (ForeignExport { fd_name = zonkLIdOcc env i , fd_sig_ty = undefined, fd_e_ext = co , fd_fe = spec }) zonkForeignExport _ for_imp = return for_imp -- Foreign imports don't need zonking zonkRules :: ZonkEnv -> [LRuleDecl GhcTcId] -> TcM [LRuleDecl GhcTc] zonkRules env rs = mapM (wrapLocM (zonkRule env)) rs zonkRule :: ZonkEnv -> RuleDecl GhcTcId -> TcM (RuleDecl GhcTc) zonkRule env rule@(HsRule { rd_tmvs = tm_bndrs{-::[RuleBndr TcId]-} , rd_lhs = lhs , rd_rhs = rhs }) = do { (env_inside, new_tm_bndrs) <- mapAccumLM zonk_tm_bndr env tm_bndrs ; let env_lhs = setZonkType env_inside SkolemiseFlexi -- See Note [Zonking the LHS of a RULE] ; new_lhs <- zonkLExpr env_lhs lhs ; new_rhs <- zonkLExpr env_inside rhs ; return $ rule { rd_tmvs = new_tm_bndrs , rd_lhs = new_lhs , rd_rhs = new_rhs } } where zonk_tm_bndr env (dL->L l (RuleBndr x (dL->L loc v))) = do { (env', v') <- zonk_it env v ; return (env', cL l (RuleBndr x (cL loc v'))) } zonk_tm_bndr _ (dL->L _ (RuleBndrSig {})) = panic "zonk_tm_bndr RuleBndrSig" zonk_tm_bndr _ (dL->L _ (XRuleBndr nec)) = noExtCon nec zonk_tm_bndr _ _ = panic "zonk_tm_bndr: Impossible Match" -- due to #15884 zonk_it env v | isId v = do { v' <- zonkIdBndr env v ; return (extendIdZonkEnvRec env [v'], v') } | otherwise = ASSERT( isImmutableTyVar v) zonkTyBndrX env v -- DV: used to be return (env,v) but that is plain -- wrong because we may need to go inside the kind -- of v and zonk there! zonkRule _ (XRuleDecl nec) = noExtCon nec {- ************************************************************************ * * Constraints and evidence * * ************************************************************************ -} zonkEvTerm :: ZonkEnv -> EvTerm -> TcM EvTerm zonkEvTerm env (EvExpr e) = EvExpr <$> zonkCoreExpr env e zonkEvTerm env (EvTypeable ty ev) = EvTypeable <$> zonkTcTypeToTypeX env ty <*> zonkEvTypeable env ev zonkEvTerm env (EvFun { et_tvs = tvs, et_given = evs , et_binds = ev_binds, et_body = body_id }) = do { (env0, new_tvs) <- zonkTyBndrsX env tvs ; (env1, new_evs) <- zonkEvBndrsX env0 evs ; (env2, new_ev_binds) <- zonkTcEvBinds env1 ev_binds ; let new_body_id = zonkIdOcc env2 body_id ; return (EvFun { et_tvs = new_tvs, et_given = new_evs , et_binds = new_ev_binds, et_body = new_body_id }) } zonkCoreExpr :: ZonkEnv -> CoreExpr -> TcM CoreExpr zonkCoreExpr env (Var v) | isCoVar v = Coercion <$> zonkCoVarOcc env v | otherwise = return (Var $ zonkIdOcc env v) zonkCoreExpr _ (Lit l) = return $ Lit l zonkCoreExpr env (Coercion co) = Coercion <$> zonkCoToCo env co zonkCoreExpr env (Type ty) = Type <$> zonkTcTypeToTypeX env ty zonkCoreExpr env (Cast e co) = Cast <$> zonkCoreExpr env e <*> zonkCoToCo env co zonkCoreExpr env (Tick t e) = Tick t <$> zonkCoreExpr env e -- Do we need to zonk in ticks? zonkCoreExpr env (App e1 e2) = App <$> zonkCoreExpr env e1 <*> zonkCoreExpr env e2 zonkCoreExpr env (Lam v e) = do { (env1, v') <- zonkCoreBndrX env v ; Lam v' <$> zonkCoreExpr env1 e } zonkCoreExpr env (Let bind e) = do (env1, bind') <- zonkCoreBind env bind Let bind'<$> zonkCoreExpr env1 e zonkCoreExpr env (Case scrut b ty alts) = do scrut' <- zonkCoreExpr env scrut ty' <- zonkTcTypeToTypeX env ty b' <- zonkIdBndr env b let env1 = extendIdZonkEnv env b' alts' <- mapM (zonkCoreAlt env1) alts return $ Case scrut' b' ty' alts' zonkCoreAlt :: ZonkEnv -> CoreAlt -> TcM CoreAlt zonkCoreAlt env (dc, bndrs, rhs) = do (env1, bndrs') <- zonkCoreBndrsX env bndrs rhs' <- zonkCoreExpr env1 rhs return $ (dc, bndrs', rhs') zonkCoreBind :: ZonkEnv -> CoreBind -> TcM (ZonkEnv, CoreBind) zonkCoreBind env (NonRec v e) = do v' <- zonkIdBndr env v e' <- zonkCoreExpr env e let env1 = extendIdZonkEnv env v' return (env1, NonRec v' e') zonkCoreBind env (Rec pairs) = do (env1, pairs') <- fixM go return (env1, Rec pairs') where go ~(_, new_pairs) = do let env1 = extendIdZonkEnvRec env (map fst new_pairs) pairs' <- mapM (zonkCorePair env1) pairs return (env1, pairs') zonkCorePair :: ZonkEnv -> (CoreBndr, CoreExpr) -> TcM (CoreBndr, CoreExpr) zonkCorePair env (v,e) = (,) <$> zonkIdBndr env v <*> zonkCoreExpr env e zonkEvTypeable :: ZonkEnv -> EvTypeable -> TcM EvTypeable zonkEvTypeable env (EvTypeableTyCon tycon e) = do { e' <- mapM (zonkEvTerm env) e ; return $ EvTypeableTyCon tycon e' } zonkEvTypeable env (EvTypeableTyApp t1 t2) = do { t1' <- zonkEvTerm env t1 ; t2' <- zonkEvTerm env t2 ; return (EvTypeableTyApp t1' t2') } zonkEvTypeable env (EvTypeableTrFun t1 t2) = do { t1' <- zonkEvTerm env t1 ; t2' <- zonkEvTerm env t2 ; return (EvTypeableTrFun t1' t2') } zonkEvTypeable env (EvTypeableTyLit t1) = do { t1' <- zonkEvTerm env t1 ; return (EvTypeableTyLit t1') } zonkTcEvBinds_s :: ZonkEnv -> [TcEvBinds] -> TcM (ZonkEnv, [TcEvBinds]) zonkTcEvBinds_s env bs = do { (env, bs') <- mapAccumLM zonk_tc_ev_binds env bs ; return (env, [EvBinds (unionManyBags bs')]) } zonkTcEvBinds :: ZonkEnv -> TcEvBinds -> TcM (ZonkEnv, TcEvBinds) zonkTcEvBinds env bs = do { (env', bs') <- zonk_tc_ev_binds env bs ; return (env', EvBinds bs') } zonk_tc_ev_binds :: ZonkEnv -> TcEvBinds -> TcM (ZonkEnv, Bag EvBind) zonk_tc_ev_binds env (TcEvBinds var) = zonkEvBindsVar env var zonk_tc_ev_binds env (EvBinds bs) = zonkEvBinds env bs zonkEvBindsVar :: ZonkEnv -> EvBindsVar -> TcM (ZonkEnv, Bag EvBind) zonkEvBindsVar env (EvBindsVar { ebv_binds = ref }) = do { bs <- readMutVar ref ; zonkEvBinds env (evBindMapBinds bs) } zonkEvBindsVar env (CoEvBindsVar {}) = return (env, emptyBag) zonkEvBinds :: ZonkEnv -> Bag EvBind -> TcM (ZonkEnv, Bag EvBind) zonkEvBinds env binds = {-# SCC "zonkEvBinds" #-} fixM (\ ~( _, new_binds) -> do { let env1 = extendIdZonkEnvRec env (collect_ev_bndrs new_binds) ; binds' <- mapBagM (zonkEvBind env1) binds ; return (env1, binds') }) where collect_ev_bndrs :: Bag EvBind -> [EvVar] collect_ev_bndrs = foldr add [] add (EvBind { eb_lhs = var }) vars = var : vars zonkEvBind :: ZonkEnv -> EvBind -> TcM EvBind zonkEvBind env bind@(EvBind { eb_lhs = var, eb_rhs = term }) = do { var' <- {-# SCC "zonkEvBndr" #-} zonkEvBndr env var -- Optimise the common case of Refl coercions -- See Note [Optimise coercion zonking] -- This has a very big effect on some programs (eg #5030) ; term' <- case getEqPredTys_maybe (idType var') of Just (r, ty1, ty2) | ty1 `eqType` ty2 -> return (evCoercion (mkTcReflCo r ty1)) _other -> zonkEvTerm env term ; return (bind { eb_lhs = var', eb_rhs = term' }) } {- Note [Optimise coercion zonking] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ When optimising evidence binds we may come across situations where a coercion looks like cv = ReflCo ty or cv1 = cv2 where the type 'ty' is big. In such cases it is a waste of time to zonk both * The variable on the LHS * The coercion on the RHS Rather, we can zonk the variable, and if its type is (ty ~ ty), we can just use Refl on the right, ignoring the actual coercion on the RHS. This can have a very big effect, because the constraint solver sometimes does go to a lot of effort to prove Refl! (Eg when solving 10+3 = 10+3; cf #5030) ************************************************************************ * * Zonking types * * ************************************************************************ -} {- Note [Sharing when zonking to Type] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Problem: In TcMType.zonkTcTyVar, we short-circuit (Indirect ty) to (Indirect zty), see Note [Sharing in zonking] in TcMType. But we /can't/ do this when zonking a TcType to a Type (#15552, esp comment:3). Suppose we have alpha -> alpha where alpha is already unified: alpha := T{tc-tycon} Int -> Int and T is knot-tied By "knot-tied" I mean that the occurrence of T is currently a TcTyCon, but the global env contains a mapping "T" :-> T{knot-tied-tc}. See Note [Type checking recursive type and class declarations] in TcTyClsDecls. Now we call zonkTcTypeToType on that (alpha -> alpha). If we follow the same path as Note [Sharing in zonking] in TcMType, we'll update alpha to alpha := T{knot-tied-tc} Int -> Int But alas, if we encounter alpha for a /second/ time, we end up looking at T{knot-tied-tc} and fall into a black hole. The whole point of zonkTcTypeToType is that it produces a type full of knot-tied tycons, and you must not look at the result!! To put it another way (zonkTcTypeToType . zonkTcTypeToType) is not the same as zonkTcTypeToType. (If we distinguished TcType from Type, this issue would have been a type error!) Solution: (see #15552 for other variants) One possible solution is simply not to do the short-circuiting. That has less sharing, but maybe sharing is rare. And indeed, that turns out to be viable from a perf point of view But the code implements something a bit better * ZonkEnv contains ze_meta_tv_env, which maps from a MetaTyVar (unificaion variable) to a Type (not a TcType) * In zonkTyVarOcc, we check this map to see if we have zonked this variable before. If so, use the previous answer; if not zonk it, and extend the map. * The map is of course stateful, held in a TcRef. (That is unlike the treatment of lexically-scoped variables in ze_tv_env and ze_id_env.) Is the extra work worth it? Some non-sytematic perf measurements suggest that compiler allocation is reduced overall (by 0.5% or so) but compile time really doesn't change. -} zonkTyVarOcc :: ZonkEnv -> TyVar -> TcM TcType zonkTyVarOcc env@(ZonkEnv { ze_flexi = flexi , ze_tv_env = tv_env , ze_meta_tv_env = mtv_env_ref }) tv | isTcTyVar tv = case tcTyVarDetails tv of SkolemTv {} -> lookup_in_tv_env RuntimeUnk {} -> lookup_in_tv_env MetaTv { mtv_ref = ref } -> do { mtv_env <- readTcRef mtv_env_ref -- See Note [Sharing when zonking to Type] ; case lookupVarEnv mtv_env tv of Just ty -> return ty Nothing -> do { mtv_details <- readTcRef ref ; zonk_meta mtv_env ref mtv_details } } | otherwise = lookup_in_tv_env where lookup_in_tv_env -- Look up in the env just as we do for Ids = case lookupVarEnv tv_env tv of Nothing -> mkTyVarTy <$> updateTyVarKindM (zonkTcTypeToTypeX env) tv Just tv' -> return (mkTyVarTy tv') zonk_meta mtv_env ref Flexi = do { kind <- zonkTcTypeToTypeX env (tyVarKind tv) ; ty <- commitFlexi flexi tv kind ; writeMetaTyVarRef tv ref ty -- Belt and braces ; finish_meta mtv_env ty } zonk_meta mtv_env _ (Indirect ty) = do { zty <- zonkTcTypeToTypeX env ty ; finish_meta mtv_env zty } finish_meta mtv_env ty = do { let mtv_env' = extendVarEnv mtv_env tv ty ; writeTcRef mtv_env_ref mtv_env' ; return ty } lookupTyVarOcc :: ZonkEnv -> TcTyVar -> Maybe TyVar lookupTyVarOcc (ZonkEnv { ze_tv_env = tv_env }) tv = lookupVarEnv tv_env tv commitFlexi :: ZonkFlexi -> TcTyVar -> Kind -> TcM Type -- Only monadic so we can do tc-tracing commitFlexi flexi tv zonked_kind = case flexi of SkolemiseFlexi -> return (mkTyVarTy (mkTyVar name zonked_kind)) DefaultFlexi | isRuntimeRepTy zonked_kind -> do { traceTc "Defaulting flexi tyvar to LiftedRep:" (pprTyVar tv) ; return liftedRepTy } | otherwise -> do { traceTc "Defaulting flexi tyvar to Any:" (pprTyVar tv) ; return (anyTypeOfKind zonked_kind) } RuntimeUnkFlexi -> do { traceTc "Defaulting flexi tyvar to RuntimeUnk:" (pprTyVar tv) ; return (mkTyVarTy (mkTcTyVar name zonked_kind RuntimeUnk)) } -- This is where RuntimeUnks are born: -- otherwise-unconstrained unification variables are -- turned into RuntimeUnks as they leave the -- typechecker's monad where name = tyVarName tv zonkCoVarOcc :: ZonkEnv -> CoVar -> TcM Coercion zonkCoVarOcc (ZonkEnv { ze_tv_env = tyco_env }) cv | Just cv' <- lookupVarEnv tyco_env cv -- don't look in the knot-tied env = return $ mkCoVarCo cv' | otherwise = do { cv' <- zonkCoVar cv; return (mkCoVarCo cv') } zonkCoHole :: ZonkEnv -> CoercionHole -> TcM Coercion zonkCoHole env hole@(CoercionHole { ch_ref = ref, ch_co_var = cv }) = do { contents <- readTcRef ref ; case contents of Just co -> do { co' <- zonkCoToCo env co ; checkCoercionHole cv co' } -- This next case should happen only in the presence of -- (undeferred) type errors. Originally, I put in a panic -- here, but that caused too many uses of `failIfErrsM`. Nothing -> do { traceTc "Zonking unfilled coercion hole" (ppr hole) ; when debugIsOn $ whenNoErrs $ MASSERT2( False , text "Type-correct unfilled coercion hole" <+> ppr hole ) ; cv' <- zonkCoVar cv ; return $ mkCoVarCo cv' } } -- This will be an out-of-scope variable, but keeping -- this as a coercion hole led to #15787 zonk_tycomapper :: TyCoMapper ZonkEnv TcM zonk_tycomapper = TyCoMapper { tcm_tyvar = zonkTyVarOcc , tcm_covar = zonkCoVarOcc , tcm_hole = zonkCoHole , tcm_tycobinder = \env tv _vis -> zonkTyBndrX env tv , tcm_tycon = zonkTcTyConToTyCon } -- Zonk a TyCon by changing a TcTyCon to a regular TyCon zonkTcTyConToTyCon :: TcTyCon -> TcM TyCon zonkTcTyConToTyCon tc | isTcTyCon tc = do { thing <- tcLookupGlobalOnly (getName tc) ; case thing of ATyCon real_tc -> return real_tc _ -> pprPanic "zonkTcTyCon" (ppr tc $$ ppr thing) } | otherwise = return tc -- it's already zonked -- Confused by zonking? See Note [What is zonking?] in TcMType. zonkTcTypeToType :: TcType -> TcM Type zonkTcTypeToType ty = initZonkEnv $ \ ze -> zonkTcTypeToTypeX ze ty zonkTcTypeToTypeX :: ZonkEnv -> TcType -> TcM Type zonkTcTypeToTypeX = mapType zonk_tycomapper zonkTcTypesToTypes :: [TcType] -> TcM [Type] zonkTcTypesToTypes tys = initZonkEnv $ \ ze -> zonkTcTypesToTypesX ze tys zonkTcTypesToTypesX :: ZonkEnv -> [TcType] -> TcM [Type] zonkTcTypesToTypesX env tys = mapM (zonkTcTypeToTypeX env) tys zonkCoToCo :: ZonkEnv -> Coercion -> TcM Coercion zonkCoToCo = mapCoercion zonk_tycomapper zonkTcMethInfoToMethInfoX :: ZonkEnv -> TcMethInfo -> TcM MethInfo zonkTcMethInfoToMethInfoX ze (name, ty, gdm_spec) = do { ty' <- zonkTcTypeToTypeX ze ty ; gdm_spec' <- zonk_gdm gdm_spec ; return (name, ty', gdm_spec') } where zonk_gdm :: Maybe (DefMethSpec (SrcSpan, TcType)) -> TcM (Maybe (DefMethSpec (SrcSpan, Type))) zonk_gdm Nothing = return Nothing zonk_gdm (Just VanillaDM) = return (Just VanillaDM) zonk_gdm (Just (GenericDM (loc, ty))) = do { ty' <- zonkTcTypeToTypeX ze ty ; return (Just (GenericDM (loc, ty'))) } --------------------------------------- {- Note [Zonking the LHS of a RULE] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ See also DsBinds Note [Free tyvars on rule LHS] We need to gather the type variables mentioned on the LHS so we can quantify over them. Example: data T a = C foo :: T a -> Int foo C = 1 {-# RULES "myrule" foo C = 1 #-} After type checking the LHS becomes (foo alpha (C alpha)) and we do not want to zap the unbound meta-tyvar 'alpha' to Any, because that limits the applicability of the rule. Instead, we want to quantify over it! We do this in two stages. * During zonking, we skolemise the TcTyVar 'alpha' to TyVar 'a'. We do this by using zonkTvSkolemising as the UnboundTyVarZonker in the ZonkEnv. (This is in fact the whole reason that the ZonkEnv has a UnboundTyVarZonker.) * In DsBinds, we quantify over it. See DsBinds Note [Free tyvars on rule LHS] Quantifying here is awkward because (a) the data type is big and (b) finding the free type vars of an expression is necessarily monadic operation. (consider /\a -> f @ b, where b is side-effected to a) -}