ghc-7.0.3: 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

- type VarEnv elt = UniqFM elt
- type IdEnv elt = VarEnv elt
- type TyVarEnv elt = VarEnv elt
- emptyVarEnv :: VarEnv a
- unitVarEnv :: Var -> a -> VarEnv a
- mkVarEnv :: [(Var, a)] -> VarEnv a
- elemVarEnv :: Var -> VarEnv a -> Bool
- varEnvElts :: VarEnv a -> [a]
- varEnvKeys :: VarEnv a -> [Unique]
- extendVarEnv :: VarEnv a -> Var -> a -> VarEnv a
- extendVarEnv_C :: (a -> a -> a) -> VarEnv a -> Var -> a -> VarEnv a
- extendVarEnv_Acc :: (a -> b -> b) -> (a -> b) -> VarEnv b -> Var -> a -> VarEnv b
- extendVarEnvList :: VarEnv a -> [(Var, a)] -> VarEnv a
- plusVarEnv :: VarEnv a -> VarEnv a -> VarEnv a
- plusVarEnv_C :: (a -> a -> a) -> VarEnv a -> VarEnv a -> VarEnv a
- delVarEnvList :: VarEnv a -> [Var] -> VarEnv a
- delVarEnv :: VarEnv a -> Var -> VarEnv a
- minusVarEnv :: VarEnv a -> VarEnv a -> VarEnv a
- intersectsVarEnv :: VarEnv a -> VarEnv a -> Bool
- lookupVarEnv :: VarEnv a -> Var -> Maybe a
- lookupVarEnv_NF :: VarEnv a -> Var -> a
- lookupWithDefaultVarEnv :: VarEnv a -> a -> Var -> a
- mapVarEnv :: (a -> b) -> VarEnv a -> VarEnv b
- zipVarEnv :: [Var] -> [a] -> VarEnv a
- modifyVarEnv :: (a -> a) -> VarEnv a -> Var -> VarEnv a
- modifyVarEnv_Directly :: (a -> a) -> UniqFM a -> Unique -> UniqFM a
- isEmptyVarEnv :: VarEnv a -> Bool
- foldVarEnv :: (a -> b -> b) -> b -> VarEnv a -> b
- elemVarEnvByKey :: Unique -> VarEnv a -> Bool
- lookupVarEnv_Directly :: VarEnv a -> Unique -> Maybe a
- filterVarEnv_Directly :: (Unique -> a -> Bool) -> VarEnv a -> VarEnv a
- restrictVarEnv :: VarEnv a -> VarSet -> VarEnv a
- data InScopeSet
- emptyInScopeSet :: InScopeSet
- mkInScopeSet :: VarEnv Var -> InScopeSet
- delInScopeSet :: InScopeSet -> Var -> InScopeSet
- extendInScopeSet :: InScopeSet -> Var -> InScopeSet
- extendInScopeSetList :: InScopeSet -> [Var] -> InScopeSet
- extendInScopeSetSet :: InScopeSet -> VarEnv Var -> InScopeSet
- getInScopeVars :: InScopeSet -> VarEnv Var
- lookupInScope :: InScopeSet -> Var -> Maybe Var
- lookupInScope_Directly :: InScopeSet -> Unique -> Maybe Var
- unionInScope :: InScopeSet -> InScopeSet -> InScopeSet
- elemInScopeSet :: Var -> InScopeSet -> Bool
- uniqAway :: InScopeSet -> Var -> Var
- data RnEnv2
- mkRnEnv2 :: InScopeSet -> RnEnv2
- rnBndr2 :: RnEnv2 -> Var -> Var -> RnEnv2
- rnBndrs2 :: RnEnv2 -> [Var] -> [Var] -> RnEnv2
- rnOccL :: RnEnv2 -> Var -> Var
- rnOccR :: RnEnv2 -> Var -> Var
- inRnEnvL :: RnEnv2 -> Var -> Bool
- inRnEnvR :: RnEnv2 -> Var -> Bool
- rnBndrL :: RnEnv2 -> Var -> (RnEnv2, Var)
- rnBndrR :: RnEnv2 -> Var -> (RnEnv2, Var)
- nukeRnEnvL :: RnEnv2 -> RnEnv2
- nukeRnEnvR :: RnEnv2 -> RnEnv2
- addRnInScopeSet :: RnEnv2 -> VarEnv Var -> RnEnv2
- rnEtaL :: RnEnv2 -> Var -> (RnEnv2, Var)
- rnEtaR :: RnEnv2 -> Var -> (RnEnv2, Var)
- rnInScope :: Var -> RnEnv2 -> Bool
- rnInScopeSet :: RnEnv2 -> InScopeSet
- lookupRnInScope :: RnEnv2 -> Var -> Var
- type TidyEnv = (TidyOccEnv, VarEnv Var)
- emptyTidyEnv :: TidyEnv

# Var, Id and TyVar environments (maps)

type VarEnv elt = UniqFM elt

type IdEnv elt = VarEnv elt

type TyVarEnv elt = VarEnv elt

## Manipulating these environments

emptyVarEnv :: VarEnv a

unitVarEnv :: Var -> a -> VarEnv a

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

elemVarEnv :: Var -> VarEnv a -> Bool

varEnvElts :: VarEnv a -> [a]

varEnvKeys :: VarEnv a -> [Unique]

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

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

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

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

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

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

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

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

minusVarEnv :: VarEnv a -> VarEnv a -> VarEnv a

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

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

lookupVarEnv_NF :: VarEnv a -> Var -> a

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

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

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

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

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

isEmptyVarEnv :: VarEnv a -> Bool

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

elemVarEnvByKey :: Unique -> VarEnv a -> Bool

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

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

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

# The InScopeSet type

data InScopeSet

A set of variables that are in scope at some point

Instances

Outputable InScopeSet |

## Operations on InScopeSets

emptyInScopeSet :: InScopeSet

mkInScopeSet :: VarEnv Var -> InScopeSet

delInScopeSet :: InScopeSet -> Var -> InScopeSet

extendInScopeSet :: InScopeSet -> Var -> InScopeSet

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

extendInScopeSetSet :: InScopeSet -> VarEnv Var -> InScopeSet

getInScopeVars :: InScopeSet -> VarEnv Var

lookupInScope :: InScopeSet -> Var -> Maybe Var

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

unionInScope :: InScopeSet -> InScopeSet -> InScopeSet

elemInScopeSet :: Var -> InScopeSet -> Bool

uniqAway :: InScopeSet -> Var -> Var

`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

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:

1. A renaming for the left-hand expression
2. A renaming for the right-hand expressions
3. 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

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

`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

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

rnOccL :: RnEnv2 -> Var -> Var

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

rnOccR :: RnEnv2 -> Var -> Var

inRnEnvL :: RnEnv2 -> Var -> Bool

Tells whether a variable is locally bound

inRnEnvR :: RnEnv2 -> Var -> Bool

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

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

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

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

nukeRnEnvL :: RnEnv2 -> RnEnv2

Wipe the left or right side renaming

nukeRnEnvR :: RnEnv2 -> RnEnv2

addRnInScopeSet :: RnEnv2 -> VarEnv Var -> RnEnv2

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

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

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

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

rnInScope :: Var -> RnEnv2 -> Bool

rnInScopeSet :: RnEnv2 -> InScopeSet

lookupRnInScope :: RnEnv2 -> Var -> Var

# TidyEnv and its operation

type TidyEnv = (TidyOccEnv, VarEnv Var)

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