ghc-9.6.0.20230111: The GHC API
Safe HaskellSafe-Inferred
LanguageHaskell2010

GHC.Core.TyCo.FVs

Synopsis

Documentation

tyCoVarsOfTypeDSet :: Type -> DTyCoVarSet Source #

tyCoFVsOfType that returns free variables of a type in a deterministic set. For explanation of why using VarSet is not deterministic see Note [Deterministic FV] in GHC.Utils.FV.

tyCoVarsOfTypesDSet :: [Type] -> DTyCoVarSet Source #

Returns free variables of types, including kind variables as a deterministic set. For type synonyms it does not expand the synonym.

tyCoFVsOfType :: Type -> FV Source #

The worker for tyCoFVsOfType and tyCoFVsOfTypeList. The previous implementation used unionVarSet which is O(n+m) and can make the function quadratic. It's exported, so that it can be composed with other functions that compute free variables. See Note [FV naming conventions] in GHC.Utils.FV.

Eta-expanded because that makes it run faster (apparently) See Note [FV eta expansion] in GHC.Utils.FV for explanation.

tyCoVarsOfTypeList :: Type -> [TyCoVar] Source #

tyCoFVsOfType that returns free variables of a type in deterministic order. For explanation of why using VarSet is not deterministic see Note [Deterministic FV] in GHC.Utils.FV.

tyCoVarsOfTypesList :: [Type] -> [TyCoVar] Source #

Returns free variables of types, including kind variables as a deterministically ordered list. For type synonyms it does not expand the synonym.

shallowTyCoVarsOfTyVarEnv :: TyVarEnv Type -> TyCoVarSet Source #

Returns free variables of types, including kind variables as a non-deterministic set. For type synonyms it does not expand the synonym.

tyCoVarsOfCoDSet :: Coercion -> DTyCoVarSet Source #

Get a deterministic set of the vars free in a coercion

almostDevoidCoVarOfCo :: CoVar -> Coercion -> Bool Source #

Given a covar and a coercion, returns True if covar is almost devoid in the coercion. That is, covar can only appear in Refl and GRefl. See last wrinkle in Note [Unused coercion variable in ForAllCo] in GHC.Core.Coercion

injectiveVarsOfType Source #

Arguments

:: Bool

Should we look under injective type families? See Note [Coverage condition for injective type families] in GHC.Tc.Instance.Family.

-> Type 
-> FV 

Returns the free variables of a Type that are in injective positions. Specifically, it finds the free variables while:

  • Expanding type synonyms
  • Ignoring the coercion in (ty |> co)
  • Ignoring the non-injective fields of a TyConApp

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

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

If injectiveVarsOfType ty = itvs, then knowing ty fixes itvs. 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.

See Note [When does a tycon application need an explicit kind signature?].

injectiveVarsOfTypes Source #

Arguments

:: Bool

look under injective type families? See Note [Coverage condition for injective type families] in GHC.Tc.Instance.Family.

-> [Type] 
-> FV 

Returns the free variables of a Type that are in injective positions. Specifically, it finds the free variables while:

  • Expanding type synonyms
  • Ignoring the coercion in (ty |> co)
  • Ignoring the non-injective fields of a TyConApp

See Note [When does a tycon application need an explicit kind signature?].

invisibleVarsOfType :: Type -> FV Source #

Returns the set of variables that are used invisibly anywhere within the given type. A variable will be included even if it is used both visibly and invisibly. An invisible use site includes: * In the kind of a variable * In the kind of a bound variable in a forall * In a coercion * In a Specified or Inferred argument to a function See Note [VarBndrs, ForAllTyBinders, TyConBinders, and visibility] in GHC.Core.TyCo.Rep

invisibleVarsOfTypes :: [Type] -> FV Source #

Like invisibleVarsOfType, but for many types.

Free type constructors

tyConsOfType :: Type -> UniqSet TyCon Source #

All type constructors occurring in the type; looking through type synonyms, but not newtypes. When it finds a Class, it returns the class TyCon.

Free vars with visible/invisible separate

visVarsOfType :: Type -> Pair TyCoVarSet Source #

Retrieve the free variables in this type, splitting them based on whether they are used visibly or invisibly. Invisible ones come first.

Occurrence-check expansion

Well-scoped free variables

scopedSort :: [TyCoVar] -> [TyCoVar] Source #

Do a topological sort on a list of tyvars, so that binders occur before occurrences E.g. given [ a::k, k::*, b::k ] it'll return a well-scoped list [ k::*, a::k, b::k ]

This is a deterministic sorting operation (that is, doesn't depend on Uniques).

It is also meant to be stable: that is, variables should not be reordered unnecessarily. This is specified in Note [ScopedSort] See also Note [Ordering of implicit variables] in GHC.Rename.HsType

tyCoVarsOfTypeWellScoped :: Type -> [TyVar] Source #

Get the free vars of a type in scoped order

tyCoVarsOfTypesWellScoped :: [Type] -> [TyVar] Source #

Get the free vars of types in scoped order

Closing over kinds

closeOverKindsDSet :: DTyVarSet -> DTyVarSet Source #

Add the kind variables free in the kinds of the tyvars in the given set. Returns a deterministic set.

closeOverKindsList :: [TyVar] -> [TyVar] Source #

Add the kind variables free in the kinds of the tyvars in the given set. Returns a deterministically ordered list.

Raw materials

newtype Endo a Source #

The monoid of endomorphisms under composition.

>>> let computation = Endo ("Hello, " ++) <> Endo (++ "!")
>>> appEndo computation "Haskell"
"Hello, Haskell!"

Constructors

Endo 

Fields

Instances

Instances details
Monoid (Endo a)

Since: base-2.1

Instance details

Defined in Data.Semigroup.Internal

Methods

mempty :: Endo a Source #

mappend :: Endo a -> Endo a -> Endo a Source #

mconcat :: [Endo a] -> Endo a Source #

Semigroup (Endo a)

Since: base-4.9.0.0

Instance details

Defined in Data.Semigroup.Internal

Methods

(<>) :: Endo a -> Endo a -> Endo a Source #

sconcat :: NonEmpty (Endo a) -> Endo a Source #

stimes :: Integral b => b -> Endo a -> Endo a Source #

Generic (Endo a) 
Instance details

Defined in Data.Semigroup.Internal

Associated Types

type Rep (Endo a) :: Type -> Type Source #

Methods

from :: Endo a -> Rep (Endo a) x Source #

to :: Rep (Endo a) x -> Endo a Source #

type Rep (Endo a)

Since: base-4.7.0.0

Instance details

Defined in Data.Semigroup.Internal

type Rep (Endo a) = D1 ('MetaData "Endo" "Data.Semigroup.Internal" "base" 'True) (C1 ('MetaCons "Endo" 'PrefixI 'True) (S1 ('MetaSel ('Just "appEndo") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 (a -> a))))