ghc-lib-parser-9.10.1.20250103: The GHC API, decoupled from GHC versions

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Language | GHC2021

GHC.Core.TyCo.Subst

Contents

- Substitutions

Description

Substitution into types and coercions.

Synopsis

- data Subst = Subst InScopeSet IdSubstEnv TvSubstEnv CvSubstEnv
- type TvSubstEnv = TyVarEnv Type
- type CvSubstEnv = CoVarEnv Coercion
- type IdSubstEnv = IdEnv CoreExpr
- emptyIdSubstEnv :: IdSubstEnv
- emptyTvSubstEnv :: TvSubstEnv
- emptyCvSubstEnv :: CvSubstEnv
- composeTCvSubst :: Subst -> Subst -> Subst
- emptySubst :: Subst
- mkEmptySubst :: InScopeSet -> Subst
- isEmptyTCvSubst :: Subst -> Bool
- isEmptySubst :: Subst -> Bool
- mkTCvSubst :: InScopeSet -> TvSubstEnv -> CvSubstEnv -> Subst
- mkTvSubst :: InScopeSet -> TvSubstEnv -> Subst
- mkCvSubst :: InScopeSet -> CvSubstEnv -> Subst
- mkIdSubst :: InScopeSet -> IdSubstEnv -> Subst
- getTvSubstEnv :: Subst -> TvSubstEnv
- getIdSubstEnv :: Subst -> IdSubstEnv
- getCvSubstEnv :: Subst -> CvSubstEnv
- getSubstInScope :: Subst -> InScopeSet
- setInScope :: Subst -> InScopeSet -> Subst
- getSubstRangeTyCoFVs :: Subst -> VarSet
- isInScope :: Var -> Subst -> Bool
- elemSubst :: Var -> Subst -> Bool
- notElemSubst :: Var -> Subst -> Bool
- zapSubst :: Subst -> Subst
- extendSubstInScope :: Subst -> Var -> Subst
- extendSubstInScopeList :: Subst -> [Var] -> Subst
- extendSubstInScopeSet :: Subst -> VarSet -> Subst
- extendTCvSubst :: Subst -> TyCoVar -> Type -> Subst
- extendTCvSubstWithClone :: Subst -> TyCoVar -> TyCoVar -> Subst
- extendCvSubst :: Subst -> CoVar -> Coercion -> Subst
- extendCvSubstWithClone :: Subst -> CoVar -> CoVar -> Subst
- extendTvSubst :: Subst -> TyVar -> Type -> Subst
- extendTvSubstWithClone :: Subst -> TyVar -> TyVar -> Subst
- extendTvSubstList :: Subst -> [(TyVar, Type)] -> Subst
- extendTvSubstAndInScope :: Subst -> TyVar -> Type -> Subst
- extendTCvSubstList :: Subst -> [Var] -> [Type] -> Subst
- unionSubst :: Subst -> Subst -> Subst
- zipTyEnv :: HasDebugCallStack => [TyVar] -> [Type] -> TvSubstEnv
- zipCoEnv :: HasDebugCallStack => [CoVar] -> [Coercion] -> CvSubstEnv
- zipTvSubst :: HasDebugCallStack => [TyVar] -> [Type] -> Subst
- zipCvSubst :: HasDebugCallStack => [CoVar] -> [Coercion] -> Subst
- zipTCvSubst :: HasDebugCallStack => [TyCoVar] -> [Type] -> Subst
- mkTvSubstPrs :: [(TyVar, Type)] -> Subst
- substTyWith :: HasDebugCallStack => [TyVar] -> [Type] -> Type -> Type
- substTyWithCoVars :: [CoVar] -> [Coercion] -> Type -> Type
- substTysWith :: HasDebugCallStack => [TyVar] -> [Type] -> [Type] -> [Type]
- substTysWithCoVars :: HasDebugCallStack => [CoVar] -> [Coercion] -> [Type] -> [Type]
- substCoWith :: HasDebugCallStack => [TyVar] -> [Type] -> Coercion -> Coercion
- substTy :: HasDebugCallStack => Subst -> Type -> Type
- substTyAddInScope :: HasDebugCallStack => Subst -> Type -> Type
- substScaledTy :: HasDebugCallStack => Subst -> Scaled Type -> Scaled Type
- substTyUnchecked :: Subst -> Type -> Type
- substTysUnchecked :: Subst -> [Type] -> [Type]
- substScaledTysUnchecked :: Subst -> [Scaled Type] -> [Scaled Type]
- substThetaUnchecked :: Subst -> ThetaType -> ThetaType
- substTyWithUnchecked :: [TyVar] -> [Type] -> Type -> Type
- substScaledTyUnchecked :: HasDebugCallStack => Subst -> Scaled Type -> Scaled Type
- substCoUnchecked :: Subst -> Coercion -> Coercion
- substCoWithUnchecked :: [TyVar] -> [Type] -> Coercion -> Coercion
- substTyWithInScope :: HasDebugCallStack => InScopeSet -> [TyVar] -> [Type] -> Type -> Type
- substTys :: HasDebugCallStack => Subst -> [Type] -> [Type]
- substScaledTys :: HasDebugCallStack => Subst -> [Scaled Type] -> [Scaled Type]
- substTheta :: HasDebugCallStack => Subst -> ThetaType -> ThetaType
- lookupTyVar :: Subst -> TyVar -> Maybe Type
- substCo :: HasDebugCallStack => Subst -> Coercion -> Coercion
- substCos :: HasDebugCallStack => Subst -> [Coercion] -> [Coercion]
- substCoVar :: Subst -> CoVar -> Coercion
- substCoVars :: Subst -> [CoVar] -> [Coercion]
- lookupCoVar :: Subst -> Var -> Maybe Coercion
- cloneTyVarBndr :: Subst -> TyVar -> Unique -> (Subst, TyVar)
- cloneTyVarBndrs :: Subst -> [TyVar] -> UniqSupply -> (Subst, [TyVar])
- substVarBndr :: HasDebugCallStack => Subst -> TyCoVar -> (Subst, TyCoVar)
- substVarBndrs :: HasDebugCallStack => Subst -> [TyCoVar] -> (Subst, [TyCoVar])
- substTyVarBndr :: HasDebugCallStack => Subst -> TyVar -> (Subst, TyVar)
- substTyVarBndrs :: HasDebugCallStack => Subst -> [TyVar] -> (Subst, [TyVar])
- substCoVarBndr :: HasDebugCallStack => Subst -> CoVar -> (Subst, CoVar)
- substTyVar :: Subst -> TyVar -> Type
- substTyVars :: Subst -> [TyVar] -> [Type]
- substTyVarToTyVar :: HasDebugCallStack => Subst -> TyVar -> TyVar
- substTyCoVars :: Subst -> [TyCoVar] -> [Type]
- substTyCoBndr :: Subst -> PiTyBinder -> (Subst, PiTyBinder)
- substForAllCoBndr :: Subst -> TyCoVar -> KindCoercion -> (Subst, TyCoVar, Coercion)
- substVarBndrUsing :: (Subst -> Type -> Type) -> Subst -> TyCoVar -> (Subst, TyCoVar)
- substForAllCoBndrUsing :: Bool -> (Coercion -> Coercion) -> Subst -> TyCoVar -> KindCoercion -> (Subst, TyCoVar, KindCoercion)
- checkValidSubst :: HasDebugCallStack => Subst -> [Type] -> [Coercion] -> a -> a
- isValidTCvSubst :: Subst -> Bool

# Substitutions

data Subst #

Type & coercion & id substitution

The Subst data type defined in this module contains substitution for tyvar, covar and id. However, operations on IdSubstEnv (mapping from Id to CoreExpr) that require the definition of the Expr data type are defined in GHC.Core.Subst to avoid circular module dependency.

Constructors

Subst InScopeSet IdSubstEnv TvSubstEnv CvSubstEnv |

#### Instances

Instances details

Outputable Subst # |
Instance details Defined in GHC.Core.TyCo.Subst Methods ppr :: Subst -> SDoc #

type TvSubstEnv = TyVarEnv Type #

A substitution of `Type`s for `TyVar`s and `Kind`s for `KindVar`s

type CvSubstEnv = CoVarEnv Coercion #

A substitution of `Coercion`s for `CoVar`s

type IdSubstEnv = IdEnv CoreExpr #

A substitution of `Expr`s for non-coercion `Id`s

emptyIdSubstEnv :: IdSubstEnv #

emptyTvSubstEnv :: TvSubstEnv #

emptyCvSubstEnv :: CvSubstEnv #

composeTCvSubst :: Subst -> Subst -> Subst #

Composes two substitutions, applying the second one provided first, like in function composition. This function leaves IdSubstEnv untouched because IdSubstEnv is not used during substitution for types.

emptySubst :: Subst #

mkEmptySubst :: InScopeSet -> Subst #

isEmptyTCvSubst :: Subst -> Bool #

Checks whether the tyvar and covar environments are empty. This function should be used over `isEmptySubst` when substituting for types, because types currently do not contain expressions; we can safely disregard the expression environment when deciding whether to skip a substitution. Using `isEmptyTCvSubst` gives us a non-trivial performance boost (up to 70% less allocation for T18223)

isEmptySubst :: Subst -> Bool #

mkTCvSubst :: InScopeSet -> TvSubstEnv -> CvSubstEnv -> Subst #

mkTvSubst :: InScopeSet -> TvSubstEnv -> Subst #

Make a TCvSubst with specified tyvar subst and empty covar subst

mkCvSubst :: InScopeSet -> CvSubstEnv -> Subst #

Make a TCvSubst with specified covar subst and empty tyvar subst

mkIdSubst :: InScopeSet -> IdSubstEnv -> Subst #

getTvSubstEnv :: Subst -> TvSubstEnv #

getIdSubstEnv :: Subst -> IdSubstEnv #

getCvSubstEnv :: Subst -> CvSubstEnv #

getSubstInScope :: Subst -> InScopeSet #

Find the in-scope set: see Note [The substitution invariant]

setInScope :: Subst -> InScopeSet -> Subst #

getSubstRangeTyCoFVs :: Subst -> VarSet #

Returns the free variables of the types in the range of a substitution as a non-deterministic set.

isInScope :: Var -> Subst -> Bool #

elemSubst :: Var -> Subst -> Bool #

notElemSubst :: Var -> Subst -> Bool #

zapSubst :: Subst -> Subst #

Remove all substitutions that might have been built up while preserving the in-scope set originally called zapSubstEnv

extendSubstInScope :: Subst -> Var -> Subst #

Add the `Var` to the in-scope set

extendSubstInScopeList :: Subst -> [Var] -> Subst #

Add the `Var`s to the in-scope set: see also `extendInScope`

extendSubstInScopeSet :: Subst -> VarSet -> Subst #

Add the `Var`s to the in-scope set: see also `extendInScope`

extendTCvSubst :: Subst -> TyCoVar -> Type -> Subst #

extendTCvSubstWithClone :: Subst -> TyCoVar -> TyCoVar -> Subst #

extendCvSubst :: Subst -> CoVar -> Coercion -> Subst #

Add a substitution from a `CoVar` to a `Coercion` to the `Subst`: you must ensure that the in-scope set satisfies Note [The substitution invariant] after extending the substitution like this

extendCvSubstWithClone :: Subst -> CoVar -> CoVar -> Subst #

extendTvSubst :: Subst -> TyVar -> Type -> Subst #

Add a substitution for a `TyVar` to the `Subst` The `TyVar` *must* be a real TyVar, and not a CoVar You must ensure that the in-scope set is such that Note [The substitution invariant] holds after extending the substitution like this.

extendTvSubstWithClone :: Subst -> TyVar -> TyVar -> Subst #

extendTvSubstList :: Subst -> [(TyVar, Type)] -> Subst #

Adds multiple `TyVar` substitutions to the `Subst`: see also `extendTvSubst`

extendTvSubstAndInScope :: Subst -> TyVar -> Type -> Subst #

extendTCvSubstList :: Subst -> [Var] -> [Type] -> Subst #

unionSubst :: Subst -> Subst -> Subst #

zipTyEnv :: HasDebugCallStack => [TyVar] -> [Type] -> TvSubstEnv #

The InScopeSet is just a thunk so with a bit of luck it'll never be evaluated

zipCoEnv :: HasDebugCallStack => [CoVar] -> [Coercion] -> CvSubstEnv #

zipTvSubst :: HasDebugCallStack => [TyVar] -> [Type] -> Subst #

Generates the in-scope set for the `Subst` from the types in the incoming environment. No CoVars or Ids, please!

zipCvSubst :: HasDebugCallStack => [CoVar] -> [Coercion] -> Subst #

Generates the in-scope set for the `Subst` from the types in the incoming environment. No TyVars, please!

zipTCvSubst :: HasDebugCallStack => [TyCoVar] -> [Type] -> Subst #

mkTvSubstPrs :: [(TyVar, Type)] -> Subst #

Generates the in-scope set for the `TCvSubst` from the types in the incoming environment. No CoVars, please! The InScopeSet is just a thunk so with a bit of luck it'll never be evaluated

substTyWith :: HasDebugCallStack => [TyVar] -> [Type] -> Type -> Type #

Type substitution, see `zipTvSubst`

substTyWithCoVars :: [CoVar] -> [Coercion] -> Type -> Type #

Substitute covars within a type

substTysWith :: HasDebugCallStack => [TyVar] -> [Type] -> [Type] -> [Type] #

Type substitution, see `zipTvSubst`

substTysWithCoVars :: HasDebugCallStack => [CoVar] -> [Coercion] -> [Type] -> [Type] #

Type substitution, see `zipTvSubst`

substCoWith :: HasDebugCallStack => [TyVar] -> [Type] -> Coercion -> Coercion #

Coercion substitution, see `zipTvSubst`

substTy :: HasDebugCallStack => Subst -> Type -> Type #

Substitute within a `Type` The substitution has to satisfy the invariants described in Note [The substitution invariant].

substTyAddInScope :: HasDebugCallStack => Subst -> Type -> Type #

Substitute within a `Type` after adding the free variables of the type to the in-scope set. This is useful for the case when the free variables aren't already in the in-scope set or easily available. See also Note [The substitution invariant].

substScaledTy :: HasDebugCallStack => Subst -> Scaled Type -> Scaled Type #

substTyUnchecked :: Subst -> Type -> Type #

Substitute within a `Type` disabling the sanity checks. The problems that the sanity checks in substTy catch are described in Note [The substitution invariant]. The goal of #11371 is to migrate all the calls of substTyUnchecked to substTy and remove this function. Please don't use in new code.

substTysUnchecked :: Subst -> [Type] -> [Type] #

Substitute within several `Type`s disabling the sanity checks. The problems that the sanity checks in substTys catch are described in Note [The substitution invariant]. The goal of #11371 is to migrate all the calls of substTysUnchecked to substTys and remove this function. Please don't use in new code.

substScaledTysUnchecked :: Subst -> [Scaled Type] -> [Scaled Type] #

substThetaUnchecked :: Subst -> ThetaType -> ThetaType #

Substitute within a `ThetaType` disabling the sanity checks. The problems that the sanity checks in substTys catch are described in Note [The substitution invariant]. The goal of #11371 is to migrate all the calls of substThetaUnchecked to substTheta and remove this function. Please don't use in new code.

substTyWithUnchecked :: [TyVar] -> [Type] -> Type -> Type #

Type substitution, see `zipTvSubst`. Disables sanity checks. The problems that the sanity checks in substTy catch are described in Note [The substitution invariant]. The goal of #11371 is to migrate all the calls of substTyUnchecked to substTy and remove this function. Please don't use in new code.

substScaledTyUnchecked :: HasDebugCallStack => Subst -> Scaled Type -> Scaled Type #

substCoUnchecked :: Subst -> Coercion -> Coercion #

Substitute within a `Coercion` disabling sanity checks. The problems that the sanity checks in substCo catch are described in Note [The substitution invariant]. The goal of #11371 is to migrate all the calls of substCoUnchecked to substCo and remove this function. Please don't use in new code.

substCoWithUnchecked :: [TyVar] -> [Type] -> Coercion -> Coercion #

Coercion substitution, see `zipTvSubst`. Disables sanity checks. The problems that the sanity checks in substCo catch are described in Note [The substitution invariant]. The goal of #11371 is to migrate all the calls of substCoUnchecked to substCo and remove this function. Please don't use in new code.

substTyWithInScope :: HasDebugCallStack => InScopeSet -> [TyVar] -> [Type] -> Type -> Type #

Substitute tyvars within a type using a known `InScopeSet`. Pre-condition: the `in_scope` set should satisfy Note [The substitution invariant]; specifically it should include the free vars of `tys`, and of `ty` minus the domain of the subst.

substTys :: HasDebugCallStack => Subst -> [Type] -> [Type] #

Substitute within several `Type`s The substitution has to satisfy the invariants described in Note [The substitution invariant].

substScaledTys :: HasDebugCallStack => Subst -> [Scaled Type] -> [Scaled Type] #

substTheta :: HasDebugCallStack => Subst -> ThetaType -> ThetaType #

Substitute within a `ThetaType` The substitution has to satisfy the invariants described in Note [The substitution invariant].

lookupTyVar :: Subst -> TyVar -> Maybe Type #

substCo :: HasDebugCallStack => Subst -> Coercion -> Coercion #

Substitute within a `Coercion` The substitution has to satisfy the invariants described in Note [The substitution invariant].

substCos :: HasDebugCallStack => Subst -> [Coercion] -> [Coercion] #

Substitute within several `Coercion`s The substitution has to satisfy the invariants described in Note [The substitution invariant].

substCoVar :: Subst -> CoVar -> Coercion #

substCoVars :: Subst -> [CoVar] -> [Coercion] #

lookupCoVar :: Subst -> Var -> Maybe Coercion #

cloneTyVarBndr :: Subst -> TyVar -> Unique -> (Subst, TyVar) #

cloneTyVarBndrs :: Subst -> [TyVar] -> UniqSupply -> (Subst, [TyVar]) #

substVarBndr :: HasDebugCallStack => Subst -> TyCoVar -> (Subst, TyCoVar) #

substVarBndrs :: HasDebugCallStack => Subst -> [TyCoVar] -> (Subst, [TyCoVar]) #

substTyVarBndr :: HasDebugCallStack => Subst -> TyVar -> (Subst, TyVar) #

substTyVarBndrs :: HasDebugCallStack => Subst -> [TyVar] -> (Subst, [TyVar]) #

substCoVarBndr :: HasDebugCallStack => Subst -> CoVar -> (Subst, CoVar) #

substTyVar :: Subst -> TyVar -> Type #

substTyVars :: Subst -> [TyVar] -> [Type] #

substTyVarToTyVar :: HasDebugCallStack => Subst -> TyVar -> TyVar #

substTyCoVars :: Subst -> [TyCoVar] -> [Type] #

substTyCoBndr :: Subst -> PiTyBinder -> (Subst, PiTyBinder) #

substForAllCoBndr :: Subst -> TyCoVar -> KindCoercion -> (Subst, TyCoVar, Coercion) #

substVarBndrUsing :: (Subst -> Type -> Type) -> Subst -> TyCoVar -> (Subst, TyCoVar) #

substForAllCoBndrUsing :: Bool -> (Coercion -> Coercion) -> Subst -> TyCoVar -> KindCoercion -> (Subst, TyCoVar, KindCoercion) #

checkValidSubst :: HasDebugCallStack => Subst -> [Type] -> [Coercion] -> a -> a #

This checks if the substitution satisfies the invariant from Note [The substitution invariant].

isValidTCvSubst :: Subst -> Bool #

When calling `substTy` it should be the case that the in-scope set in the substitution is a superset of the free vars of the range of the substitution. See also Note [The substitution invariant]. TODO: take into account ids and rename as isValidSubst