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| Synopsis |
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| Main data types
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| data Subst |
A substitution environment, containing both Id and TyVar substitutions.
Some invariants apply to how you use the substitution:
1. The in-scope set contains at least those Ids and TyVars that will be in scope after
applying the substitution to a term. Precisely, the in-scope set must be a superset of the free vars of the
substitution range that might possibly clash with locally-bound variables in the thing being substituted in.
2. You may apply the substitution only once
There are various ways of setting up the in-scope set such that the first of these invariants hold:
- Arrange that the in-scope set really is all the things in scope
- Arrange that it's the free vars of the range of the substitution
- Make it empty, if you know that all the free vars of the substitution are fresh, and hence can't possibly clash
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| type TvSubstEnv = TyVarEnv Type |
| A substitition of Types for TyVars
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| type IdSubstEnv = IdEnv CoreExpr |
| An environment for substituting for Ids
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| data InScopeSet |
| A set of variables that are in scope at some point
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| Substituting into expressions and related types
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| deShadowBinds :: [CoreBind] -> [CoreBind] |
De-shadowing the program is sometimes a useful pre-pass. It can be done simply
by running over the bindings with an empty substitution, becuase 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.)
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| substTy :: Subst -> Type -> Type |
| See substTy
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| substExpr :: Subst -> CoreExpr -> CoreExpr |
Apply a substititon to an entire CoreExpr. Rememeber, you may only
apply the substitution once: see CoreSubst#apply_once
Do *not* attempt to short-cut in the case of an empty substitution!
See Note [Extending the Subst]
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| substSpec :: Subst -> Id -> SpecInfo -> SpecInfo |
| Substitutes for the Ids within the WorkerInfo given the new function Id
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| substWorker :: Subst -> WorkerInfo -> WorkerInfo |
| Substitutes for the Ids within the WorkerInfo
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| lookupIdSubst :: Subst -> Id -> CoreExpr |
| Find the substitution for an Id in the Subst
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| lookupTvSubst :: Subst -> TyVar -> Type |
| Find the substitution for a TyVar in the Subst
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| Operations on substitutions
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| emptySubst :: Subst |
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| mkEmptySubst :: InScopeSet -> Subst |
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| mkSubst :: InScopeSet -> TvSubstEnv -> IdSubstEnv -> Subst |
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| substInScope :: Subst -> InScopeSet |
| Find the in-scope set: see CoreSubst#in_scope_invariant
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| isEmptySubst :: Subst -> Bool |
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| extendIdSubst :: Subst -> Id -> CoreExpr -> Subst |
| Add a substitution for an Id to the Subst: you must ensure that the in-scope set is
such that the CoreSubst#in_scope_invariant is true after extending the substitution like this
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| extendIdSubstList :: Subst -> [(Id, CoreExpr)] -> Subst |
| Adds multiple Id substitutions to the Subst: see also extendIdSubst
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| extendTvSubst :: Subst -> TyVar -> Type -> Subst |
| Add a substitution for a TyVar to the Subst: you must ensure that the in-scope set is
such that the CoreSubst#in_scope_invariant is true after extending the substitution like this
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| extendTvSubstList :: Subst -> [(TyVar, Type)] -> Subst |
| Adds multiple TyVar substitutions to the Subst: see also extendTvSubst
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| extendSubst :: Subst -> Var -> CoreArg -> Subst |
| Add a substitution for a TyVar or Id as appropriate to the Var being added. See also
extendIdSubst and extendTvSubst
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| extendSubstList :: Subst -> [(Var, CoreArg)] -> Subst |
| Add a substitution for a TyVar or Id as appropriate to all the Vars being added. See also extendSubst
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| zapSubstEnv :: Subst -> Subst |
| Remove all substitutions for Ids and Vars that might have been built up
while preserving the in-scope set
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| extendInScope :: Subst -> Var -> Subst |
| Add the Var to the in-scope set: as a side effect, removes any existing substitutions for it
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| extendInScopeList :: Subst -> [Var] -> Subst |
| Add the Vars to the in-scope set: see also extendInScope
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| extendInScopeIds :: Subst -> [Id] -> Subst |
| Optimized version of extendInScopeList that can be used if you are certain
all the things being added are Ids and hence none are TyVars
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| isInScope :: Var -> Subst -> Bool |
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| Substituting and cloning binders
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| substBndr :: Subst -> Var -> (Subst, Var) |
| Substitutes a Var for another one according to the Subst given, returning
the result and an updated Subst that should be used by subsequent substitutons.
IdInfo is preserved by this process, although it is substituted into appropriately.
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| substBndrs :: Subst -> [Var] -> (Subst, [Var]) |
| Applies substBndr to a number of Vars, accumulating a new Subst left-to-right
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| substRecBndrs :: Subst -> [Id] -> (Subst, [Id]) |
| Substitute in a mutually recursive group of Ids
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| cloneIdBndr :: Subst -> UniqSupply -> Id -> (Subst, Id) |
| Very similar to substBndr, but it always allocates a new Unique for
each variable in its output and removes all IdInfo
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| cloneIdBndrs :: Subst -> UniqSupply -> [Id] -> (Subst, [Id]) |
| Applies cloneIdBndr to a number of Ids, accumulating a final
substitution from left to right
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| cloneRecIdBndrs :: Subst -> UniqSupply -> [Id] -> (Subst, [Id]) |
| Clone a mutually recursive group of Ids
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| Produced by Haddock version 2.3.0 |
