Safe Haskell | None |
---|---|
Language | Haskell98 |
InstEnv
- type DFunId = Id
- data OverlapFlag
- = NoOverlap { }
- | OverlapOk { }
- | Incoherent { }
- type InstMatch = (ClsInst, [DFunInstType])
- type ClsInstLookupResult = ([InstMatch], [ClsInst], Bool)
- data ClsInst = ClsInst {}
- type DFunInstType = Maybe Type
- pprInstance :: ClsInst -> SDoc
- pprInstanceHdr :: ClsInst -> SDoc
- pprInstances :: [ClsInst] -> SDoc
- instanceHead :: ClsInst -> ([TyVar], Class, [Type])
- instanceSig :: ClsInst -> ([TyVar], [Type], Class, [Type])
- mkLocalInstance :: DFunId -> OverlapFlag -> [TyVar] -> Class -> [Type] -> ClsInst
- mkImportedInstance :: Name -> [Maybe Name] -> DFunId -> OverlapFlag -> ClsInst
- instanceDFunId :: ClsInst -> DFunId
- tidyClsInstDFun :: (DFunId -> DFunId) -> ClsInst -> 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]
- orphNamesOfClsInst :: ClsInst -> NameSet
- instanceBindFun :: TyVar -> BindFlag
- instanceCantMatch :: [Maybe Name] -> [Maybe Name] -> Bool
- roughMatchTcs :: [Type] -> [Maybe Name]
Documentation
data OverlapFlag
The semantics allowed for overlapping instances for a particular
instance. See Note [Safe Haskell isSafeOverlap] (in lhs
) for a
explanation of the isSafeOverlap
field.
Constructors
NoOverlap | This instance must not overlap another |
Fields | |
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 | |
Incoherent | Silently ignore this instance if you find any other that matches the constraing you are trying to resolve, including when checking if there are instances that do not match, but unify. Example: constraint (Foo [b])
instances (Foo [Int]) Incoherent
(Foo [a])
Without the Incoherent flag, we'd complain that
instantiating |
Fields |
type InstMatch = (ClsInst, [DFunInstType])
type ClsInstLookupResult = ([InstMatch], [ClsInst], Bool)
type DFunInstType = Maybe Type
pprInstance :: ClsInst -> SDoc
pprInstanceHdr :: ClsInst -> SDoc
pprInstances :: [ClsInst] -> SDoc
instanceHead :: ClsInst -> ([TyVar], Class, [Type])
mkLocalInstance :: DFunId -> OverlapFlag -> [TyVar] -> Class -> [Type] -> ClsInst
mkImportedInstance :: Name -> [Maybe Name] -> DFunId -> OverlapFlag -> ClsInst
instanceDFunId :: ClsInst -> DFunId
tidyClsInstDFun :: (DFunId -> DFunId) -> ClsInst -> ClsInst
instanceRoughTcs :: ClsInst -> [Maybe Name]
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, InstEnv) -> Class -> [Type] -> ClsInstLookupResult
instEnvElts :: InstEnv -> [ClsInst]
classInstances :: (InstEnv, InstEnv) -> Class -> [ClsInst]
orphNamesOfClsInst :: ClsInst -> NameSet
Collects the names of concrete types and type constructors that make up the head of a class instance. For instance, given `class Foo a b`:
`instance Foo (Either (Maybe Int) a) Bool` would yield [Either, Maybe, Int, Bool]
Used in the implementation of ":info" in GHCi.
instanceBindFun :: TyVar -> BindFlag
roughMatchTcs :: [Type] -> [Maybe Name]