Safe Haskell	None

InstEnv

Synopsis

Documentation

type DFunId = Id Source

data OverlapFlag Source

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

data Instance Source

Constructors

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

Instances

Data Instance
Typeable Instance
Outputable Instance
NamedThing Instance

pprInstance :: Instance -> SDoc Source

pprInstanceHdr :: Instance -> SDoc Source

pprInstances :: [Instance] -> SDoc Source

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

mkLocalInstance :: DFunId -> OverlapFlag -> Instance Source

mkImportedInstance :: Name -> [Maybe Name] -> DFunId -> OverlapFlag -> Instance Source

instanceDFunId :: Instance -> DFunId Source

setInstanceDFunId :: Instance -> DFunId -> Instance Source

instanceRoughTcs :: Instance -> [Maybe Name]Source

type InstEnv = UniqFM ClsInstEnvSource

emptyInstEnv :: InstEnv Source

extendInstEnv :: InstEnv -> Instance -> InstEnv Source

overwriteInstEnv :: InstEnv -> Instance -> InstEnv Source

extendInstEnvList :: InstEnv -> [Instance] -> InstEnv Source

lookupUniqueInstEnv :: (InstEnv, InstEnv) -> Class -> [Type] -> Either Message (Instance, [Type])Source

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], [Instance])Source

lookupInstEnv :: (InstEnv, InstEnv) -> Class -> [Type] -> ([InstMatch], [Instance], Bool)Source

instEnvElts :: InstEnv -> [Instance]Source

classInstances :: (InstEnv, InstEnv) -> Class -> [Instance]Source

instanceBindFun :: TyVar -> BindFlag Source

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

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