InstEnv

ghc-7.6.3: The GHC API

Safe Haskell | None

InstEnv

Synopsis

- type DFunId = Id
- data OverlapFlag
  - = NoOverlap {
    - isSafeOverlap :: Bool
    }
  - | OverlapOk {
    - isSafeOverlap :: Bool
    }
  - | Incoherent {
    - isSafeOverlap :: Bool
    }
- type InstMatch = (ClsInst, [DFunInstType])
- type ClsInstLookupResult = ([InstMatch], [ClsInst], Bool)
- data ClsInst = ClsInst {
  - is_cls :: Name
  - is_tcs :: [Maybe Name]
  - is_tvs :: TyVarSet
  - is_tys :: [Type]
  - is_dfun :: DFunId
  - is_flag :: OverlapFlag
  }
- type DFunInstType = Maybe Type
- pprInstance :: ClsInst -> SDoc
- pprInstanceHdr :: ClsInst -> SDoc
- pprInstances :: [ClsInst] -> SDoc
- instanceHead :: ClsInst -> ([TyVar], ThetaType, Class, [Type])
- mkLocalInstance :: DFunId -> OverlapFlag -> ClsInst
- mkImportedInstance :: Name -> [Maybe Name] -> DFunId -> OverlapFlag -> ClsInst
- instanceDFunId :: ClsInst -> DFunId
- setInstanceDFunId :: ClsInst -> DFunId -> ClsInst
- instanceRoughTcs :: ClsInst -> [Maybe Name]
- type InstEnv = UniqFM ClsInstEnv
- emptyInstEnv :: InstEnv
- extendInstEnv :: InstEnv -> ClsInst -> InstEnv
- overwriteInstEnv :: InstEnv -> ClsInst -> InstEnv
- extendInstEnvList :: InstEnv -> [ClsInst] -> InstEnv
- lookupUniqueInstEnv :: (InstEnv, InstEnv) -> Class -> [Type] -> Either MsgDoc (ClsInst, [Type])
- lookupInstEnv' :: InstEnv -> Class -> [Type] -> ([InstMatch], [ClsInst])
- lookupInstEnv :: (InstEnv, InstEnv) -> Class -> [Type] -> ClsInstLookupResult
- instEnvElts :: InstEnv -> [ClsInst]
- classInstances :: (InstEnv, InstEnv) -> Class -> [ClsInst]
- instanceBindFun :: TyVar -> BindFlag
- instanceCantMatch :: [Maybe Name] -> [Maybe Name] -> Bool
- roughMatchTcs :: [Type] -> [Maybe Name]

# Documentation

type DFunId = Id

data OverlapFlag

Constructors

NoOverlap | This instance must not overlap another
Fields isSafeOverlap :: Bool
OverlapOk | Silently ignore this instance if you find a more specific one that matches the constraint you are trying to resolve Example: constraint (Foo [Int]) instances (Foo [Int]) (Foo [a]) OverlapOk Since the second instance has the OverlapOk flag, the first instance will be chosen (otherwise its ambiguous which to choose)
Fields isSafeOverlap :: Bool
Incoherent | Like OverlapOk, but also ignore this instance if it doesn't match the constraint you are trying to resolve, but could match if the type variables in the constraint were instantiated Example: constraint (Foo [b]) instances (Foo [Int]) Incoherent (Foo [a]) Without the Incoherent flag, we'd complain that instantiating `b` would change which instance was chosen
Fields isSafeOverlap :: Bool

Instances

Eq OverlapFlag |
Data OverlapFlag |
Typeable OverlapFlag |
Outputable OverlapFlag |
Binary OverlapFlag |

type InstMatch = (ClsInst, [DFunInstType])

type ClsInstLookupResult = ([InstMatch], [ClsInst], Bool)

data ClsInst

Constructors

ClsInst |
Fields is_cls :: Name is_tcs :: [Maybe Name] is_tvs :: TyVarSet is_tys :: [Type] is_dfun :: DFunId is_flag :: OverlapFlag

Instances

Data ClsInst |
Typeable ClsInst |
Outputable ClsInst |
NamedThing ClsInst |

type DFunInstType = Maybe Type

pprInstance :: ClsInst -> SDoc

pprInstanceHdr :: ClsInst -> SDoc

pprInstances :: [ClsInst] -> SDoc

instanceHead :: ClsInst -> ([TyVar], ThetaType, Class, [Type])

mkLocalInstance :: DFunId -> OverlapFlag -> ClsInst

mkImportedInstance :: Name -> [Maybe Name] -> DFunId -> OverlapFlag -> ClsInst

instanceDFunId :: ClsInst -> DFunId

setInstanceDFunId :: ClsInst -> DFunId -> ClsInst

instanceRoughTcs :: ClsInst -> [Maybe Name]

type InstEnv = UniqFM ClsInstEnv

emptyInstEnv :: InstEnv

extendInstEnv :: InstEnv -> ClsInst -> InstEnv

overwriteInstEnv :: InstEnv -> ClsInst -> InstEnv

extendInstEnvList :: InstEnv -> [ClsInst] -> InstEnv

lookupUniqueInstEnv :: (InstEnv, InstEnv) -> Class -> [Type] -> Either MsgDoc (ClsInst, [Type])

Look up an instance in the given instance environment. The given class application must match exactly one instance and the match may not contain any flexi type variables. If the lookup is unsuccessful, yield 'Left errorMessage'.

lookupInstEnv' :: InstEnv -> Class -> [Type] -> ([InstMatch], [ClsInst])

lookupInstEnv :: (InstEnv, InstEnv) -> Class -> [Type] -> ClsInstLookupResult

instEnvElts :: InstEnv -> [ClsInst]

classInstances :: (InstEnv, InstEnv) -> Class -> [ClsInst]

instanceBindFun :: TyVar -> BindFlag

instanceCantMatch :: [Maybe Name] -> [Maybe Name] -> Bool

roughMatchTcs :: [Type] -> [Maybe Name]