ghc-7.2.2: The GHC API

VarEnv

Contents

Var, Id and TyVar environments (maps)
- Manipulating these environments
The InScopeSet type
- Operations on InScopeSets
The RnEnv2 type
- Operations on RnEnv2s
TidyEnv and its operation

Synopsis

Var, Id and TyVar environments (maps)

type VarEnv elt = UniqFM eltSource

type IdEnv elt = VarEnv eltSource

type TyVarEnv elt = VarEnv eltSource

type CoVarEnv elt = VarEnv eltSource

Manipulating these environments

emptyVarEnv :: VarEnv aSource

unitVarEnv :: Var -> a -> VarEnv aSource

mkVarEnv :: [(Var, a)] -> VarEnv aSource

elemVarEnv :: Var -> VarEnv a -> Bool Source

varEnvElts :: VarEnv a -> [a]Source

varEnvKeys :: VarEnv a -> [Unique]Source

extendVarEnv :: VarEnv a -> Var -> a -> VarEnv aSource

extendVarEnv_C :: (a -> a -> a) -> VarEnv a -> Var -> a -> VarEnv aSource

extendVarEnv_Acc :: (a -> b -> b) -> (a -> b) -> VarEnv b -> Var -> a -> VarEnv bSource

extendVarEnvList :: VarEnv a -> [(Var, a)] -> VarEnv aSource

plusVarEnv :: VarEnv a -> VarEnv a -> VarEnv aSource

plusVarEnv_C :: (a -> a -> a) -> VarEnv a -> VarEnv a -> VarEnv aSource

delVarEnvList :: VarEnv a -> [Var] -> VarEnv aSource

delVarEnv :: VarEnv a -> Var -> VarEnv aSource

minusVarEnv :: VarEnv a -> VarEnv b -> VarEnv aSource

intersectsVarEnv :: VarEnv a -> VarEnv a -> Bool Source

lookupVarEnv :: VarEnv a -> Var -> Maybe aSource

lookupVarEnv_NF :: VarEnv a -> Var -> aSource

lookupWithDefaultVarEnv :: VarEnv a -> a -> Var -> aSource

mapVarEnv :: (a -> b) -> VarEnv a -> VarEnv bSource

zipVarEnv :: [Var] -> [a] -> VarEnv aSource

modifyVarEnv :: (a -> a) -> VarEnv a -> Var -> VarEnv aSource

modifyVarEnv_Directly :: (a -> a) -> UniqFM a -> Unique -> UniqFM aSource

isEmptyVarEnv :: VarEnv a -> Bool Source

foldVarEnv :: (a -> b -> b) -> b -> VarEnv a -> bSource

elemVarEnvByKey :: Unique -> VarEnv a -> Bool Source

lookupVarEnv_Directly :: VarEnv a -> Unique -> Maybe aSource

filterVarEnv_Directly :: (Unique -> a -> Bool) -> VarEnv a -> VarEnv aSource

restrictVarEnv :: VarEnv a -> VarSet -> VarEnv aSource

The InScopeSet type

data InScopeSet Source

A set of variables that are in scope at some point

Instances

Outputable InScopeSet

Operations on InScopeSets

emptyInScopeSet :: InScopeSet Source

mkInScopeSet :: VarEnv Var -> InScopeSet Source

delInScopeSet :: InScopeSet -> Var -> InScopeSet Source

extendInScopeSet :: InScopeSet -> Var -> InScopeSet Source

extendInScopeSetList :: InScopeSet -> [Var] -> InScopeSet Source

extendInScopeSetSet :: InScopeSet -> VarEnv Var -> InScopeSet Source

getInScopeVars :: InScopeSet -> VarEnv Var Source

lookupInScope :: InScopeSet -> Var -> Maybe Var Source

Look up a variable the InScopeSet. This lets you map from the variable's identity (unique) to its full value.

lookupInScope_Directly :: InScopeSet -> Unique -> Maybe Var Source

unionInScope :: InScopeSet -> InScopeSet -> InScopeSet Source

elemInScopeSet :: Var -> InScopeSet -> Bool Source

uniqAway :: InScopeSet -> Var -> Var Source

uniqAway in_scope v finds a unique that is not used in the in-scope set, and gives that to v.

The RnEnv2 type

data RnEnv2 Source

When we are comparing (or matching) types or terms, we are faced with "going under" corresponding binders. E.g. when comparing:

 \x. e1	~   \y. e2

Basically we want to rename [x -> y] or [y -> x], but there are lots of things we must be careful of. In particular, x might be free in e2, or y in e1. So the idea is that we come up with a fresh binder that is free in neither, and rename x and y respectively. That means we must maintain:

A renaming for the left-hand expression
A renaming for the right-hand expressions
An in-scope set

Furthermore, when matching, we want to be able to have an 'occurs check', to prevent:

 \x. f   ~   \y. y

matching with [f -> y]. So for each expression we want to know that set of locally-bound variables. That is precisely the domain of the mappings 1. and 2., but we must ensure that we always extend the mappings as we go in.

All of this information is bundled up in the RnEnv2

Operations on RnEnv2s

mkRnEnv2 :: InScopeSet -> RnEnv2 Source

rnBndr2 :: RnEnv2 -> Var -> Var -> RnEnv2 Source

rnBndr2 env bL bR goes under a binder bL in the Left term, and binder bR in the Right term. It finds a new binder, new_b, and returns an environment mapping bL -> new_b and bR -> new_b

rnBndrs2 :: RnEnv2 -> [Var] -> [Var] -> RnEnv2 Source

Applies rnBndr2 to several variables: the two variable lists must be of equal length

rnOccL, rnOccR :: RnEnv2 -> Var -> Var Source

Look up the renaming of an occurrence in the left or right term

inRnEnvL, inRnEnvR :: RnEnv2 -> Var -> Bool Source

Tells whether a variable is locally bound

rnOccL_maybe, rnOccR_maybe :: RnEnv2 -> Var -> Maybe Var Source

Look up the renaming of an occurrence in the left or right term

rnBndrL :: RnEnv2 -> Var -> (RnEnv2, Var)Source

Similar to rnBndr2 but used when there's a binder on the left side only.

rnBndrR :: RnEnv2 -> Var -> (RnEnv2, Var)Source

Similar to rnBndr2 but used when there's a binder on the right side only.

nukeRnEnvL, nukeRnEnvR :: RnEnv2 -> RnEnv2 Source

Wipe the left or right side renaming

delBndrL, delBndrR :: RnEnv2 -> Var -> RnEnv2 Source

delBndrsL, delBndrsR :: RnEnv2 -> [Var] -> RnEnv2 Source

addRnInScopeSet :: RnEnv2 -> VarEnv Var -> RnEnv2 Source

rnEtaL :: RnEnv2 -> Var -> (RnEnv2, Var)Source

Similar to rnBndrL but used for eta expansion See Note [Eta expansion]

rnEtaR :: RnEnv2 -> Var -> (RnEnv2, Var)Source

Similar to rnBndr2 but used for eta expansion See Note [Eta expansion]

rnInScope :: Var -> RnEnv2 -> Bool Source

rnInScopeSet :: RnEnv2 -> InScopeSet Source

lookupRnInScope :: RnEnv2 -> Var -> Var Source

TidyEnv and its operation

type TidyEnv = (TidyOccEnv, VarEnv Var)Source

When tidying up print names, we keep a mapping of in-scope occ-names (the TidyOccEnv) and a Var-to-Var of the current renamings

emptyTidyEnv :: TidyEnv Source