ghc-9.0.2: The GHC API
Safe HaskellSafe-Inferred
LanguageHaskell2010

GHC.Core.Subst

Synopsis

Main data types

data Subst Source #

A substitution environment, containing Id, TyVar, and CoVar substitutions.

Some invariants apply to how you use the substitution:

  1. Note [The substitution invariant] in GHC.Core.TyCo.Subst
  2. Note [Substitutions apply only once] in GHC.Core.TyCo.Subst

Constructors

Subst InScopeSet IdSubstEnv TvSubstEnv CvSubstEnv 

Instances

Instances details
Outputable Subst Source # 
Instance details

Defined in GHC.Core.Subst

Methods

ppr :: Subst -> SDoc Source #

pprPrec :: Rational -> Subst -> SDoc Source #

type TvSubstEnv = TyVarEnv Type Source #

A substitution of Types for TyVars and Kinds for KindVars

type IdSubstEnv = IdEnv CoreExpr Source #

An environment for substituting for Ids

data InScopeSet Source #

A set of variables that are in scope at some point "Secrets of the Glasgow Haskell Compiler inliner" Section 3.2 provides the motivation for this abstraction.

Instances

Instances details
Outputable InScopeSet Source # 
Instance details

Defined in GHC.Types.Var.Env

Methods

ppr :: InScopeSet -> SDoc Source #

pprPrec :: Rational -> InScopeSet -> SDoc Source #

Substituting into expressions and related types

deShadowBinds :: CoreProgram -> CoreProgram Source #

De-shadowing the program is sometimes a useful pre-pass. It can be done simply by running over the bindings with an empty substitution, because substitution returns a result that has no-shadowing guaranteed.

(Actually, within a single type there might still be shadowing, because substTy is a no-op for the empty substitution, but that's probably OK.)

Aug 09
This function is not used in GHC at the moment, but seems so short and simple that I'm going to leave it here

substSpec :: Subst -> Id -> RuleInfo -> RuleInfo Source #

Substitutes for the Ids within the WorkerInfo given the new function Id

substRulesForImportedIds :: Subst -> [CoreRule] -> [CoreRule] Source #

substTy :: Subst -> Type -> Type Source #

See substTy

substCo :: HasCallStack => Subst -> Coercion -> Coercion Source #

See substCo

substExpr :: HasDebugCallStack => Subst -> CoreExpr -> CoreExpr Source #

substExpr applies a substitution to an entire CoreExpr. Remember, you may only apply the substitution once: See Note [Substitutions apply only once] in GHC.Core.TyCo.Subst

Do *not* attempt to short-cut in the case of an empty substitution! See Note [Extending the Subst]

substExprSC :: HasDebugCallStack => Subst -> CoreExpr -> CoreExpr Source #

substBind :: HasDebugCallStack => Subst -> CoreBind -> (Subst, CoreBind) Source #

Apply a substitution to an entire CoreBind, additionally returning an updated Subst that should be used by subsequent substitutions.

substBindSC :: HasDebugCallStack => Subst -> CoreBind -> (Subst, CoreBind) Source #

Apply a substitution to an entire CoreBind, additionally returning an updated Subst that should be used by subsequent substitutions.

substUnfolding :: Subst -> Unfolding -> Unfolding Source #

Substitutes for the Ids within an unfolding

substUnfoldingSC :: Subst -> Unfolding -> Unfolding Source #

Substitutes for the Ids within an unfolding

lookupIdSubst :: HasDebugCallStack => Subst -> Id -> CoreExpr Source #

Find the substitution for an Id in the Subst

lookupTCvSubst :: Subst -> TyVar -> Type Source #

Find the substitution for a TyVar in the Subst

substIdType :: Subst -> Id -> Id Source #

substIdOcc :: Subst -> Id -> Id Source #

substTickish :: Subst -> Tickish Id -> Tickish Id Source #

substDVarSet :: Subst -> DVarSet -> DVarSet Source #

substIdInfo :: Subst -> Id -> IdInfo -> Maybe IdInfo Source #

Substitute into some IdInfo with regard to the supplied new Id.

Operations on substitutions

emptySubst :: Subst Source #

mkEmptySubst :: InScopeSet -> Subst Source #

mkSubst :: InScopeSet -> TvSubstEnv -> CvSubstEnv -> IdSubstEnv -> Subst Source #

mkOpenSubst :: InScopeSet -> [(Var, CoreArg)] -> Subst Source #

Simultaneously substitute for a bunch of variables No left-right shadowing ie the substitution for (x y. e) a1 a2 so neither x nor y scope over a1 a2

substInScope :: Subst -> InScopeSet Source #

Find the in-scope set: see GHC.Core.TyCo.Subst Note [The substitution invariant]

isEmptySubst :: Subst -> Bool Source #

extendIdSubst :: Subst -> Id -> CoreExpr -> Subst Source #

Add a substitution for an Id to the Subst: you must ensure that the in-scope set is such that TyCoSubst Note [The substitution invariant] holds after extending the substitution like this

extendIdSubstList :: Subst -> [(Id, CoreExpr)] -> Subst Source #

Adds multiple Id substitutions to the Subst: see also extendIdSubst

extendTCvSubst :: TCvSubst -> TyCoVar -> Type -> TCvSubst Source #

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

Adds multiple TyVar substitutions to the Subst: see also extendTvSubst

extendSubst :: Subst -> Var -> CoreArg -> Subst Source #

Add a substitution appropriate to the thing being substituted (whether an expression, type, or coercion). See also extendIdSubst, extendTvSubst, extendCvSubst

extendSubstList :: Subst -> [(Var, CoreArg)] -> Subst Source #

Add a substitution as appropriate to each of the terms being substituted (whether expressions, types, or coercions). See also extendSubst.

extendSubstWithVar :: Subst -> Var -> Var -> Subst Source #

zapSubstEnv :: Subst -> Subst Source #

Remove all substitutions for Ids and Vars that might have been built up while preserving the in-scope set

addInScopeSet :: Subst -> VarSet -> Subst Source #

Add the Var to the in-scope set, but do not remove any existing substitutions for it

extendInScope :: Subst -> Var -> Subst Source #

Add the Var to the in-scope set: as a side effect, and remove any existing substitutions for it

extendInScopeList :: Subst -> [Var] -> Subst Source #

Add the Vars to the in-scope set: see also extendInScope

extendInScopeIds :: Subst -> [Id] -> Subst Source #

Optimized version of extendInScopeList that can be used if you are certain all the things being added are Ids and hence none are TyVars or CoVars

isInScope :: Var -> Subst -> Bool Source #

setInScope :: Subst -> InScopeSet -> Subst Source #

getTCvSubst :: Subst -> TCvSubst Source #

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

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 GHC.Core.TyCo.Subst Note [The substitution invariant] holds after extending the substitution like this.

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

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

delBndr :: Subst -> Var -> Subst Source #

delBndrs :: Subst -> [Var] -> Subst Source #

Substituting and cloning binders

substBndr :: Subst -> Var -> (Subst, Var) Source #

Substitutes a Var for another one according to the Subst given, returning the result and an updated Subst that should be used by subsequent substitutions. IdInfo is preserved by this process, although it is substituted into appropriately.

substBndrs :: Subst -> [Var] -> (Subst, [Var]) Source #

Applies substBndr to a number of Vars, accumulating a new Subst left-to-right

substRecBndrs :: Subst -> [Id] -> (Subst, [Id]) Source #

Substitute in a mutually recursive group of Ids

substTyVarBndr :: Subst -> TyVar -> (Subst, TyVar) Source #

substCoVarBndr :: Subst -> CoVar -> (Subst, CoVar) Source #

cloneBndr :: Subst -> Unique -> Var -> (Subst, Var) Source #

cloneBndrs :: Subst -> UniqSupply -> [Var] -> (Subst, [Var]) Source #

cloneIdBndr :: Subst -> UniqSupply -> Id -> (Subst, Id) Source #

Very similar to substBndr, but it always allocates a new Unique for each variable in its output. It substitutes the IdInfo though.

cloneIdBndrs :: Subst -> UniqSupply -> [Id] -> (Subst, [Id]) Source #

Applies cloneIdBndr to a number of Ids, accumulating a final substitution from left to right

cloneRecIdBndrs :: Subst -> UniqSupply -> [Id] -> (Subst, [Id]) Source #

Clone a mutually recursive group of Ids