Safe Haskell | None |
---|---|
Language | Haskell2010 |
Synopsis
- magicTyFamPlugin :: String -> String -> String -> ([Type] -> Maybe Type) -> Plugin
- withStuckSemantics :: ([Type] -> Maybe Type) -> [Type] -> Maybe Type
- isTyFamFree :: Type -> Bool
- solveWanteds :: ([Type] -> Maybe Type) -> TyCon -> [Ct] -> TcPluginM [Ct]
- loadTyCon :: String -> String -> String -> TcPluginM TyCon
- data Plugin
- data TyCon
- data Type
Documentation
Generate a plugin that solves instances of the type family pointed at by the three strings, via the function.
Semantics
withStuckSemantics :: ([Type] -> Maybe Type) -> [Type] -> Maybe Type Source #
Ensure that your resulting type family preserves the stuckness property, namely that it is stuck if any of its children are stuck.
You can use isTyFamFree
instead of withStuckSemantics
if you want tigher
control over when your magic type family should be stuck.
isTyFamFree :: Type -> Bool #
Check that a type does not contain any type family applications.
Low level stuff
solveWanteds :: ([Type] -> Maybe Type) -> TyCon -> [Ct] -> TcPluginM [Ct] Source #
solveWanteds f tyfam cts
finds all instaces of tyfam
inside the wanted
constraints cts
, and evaluates them via f
. The result is a set of
CNonCanonical
constraints, which should be emitted as the second parameter
of TcPluginOk
.
Get your hands on the type constructor for your type family.
Re-exports
Plugin
is the compiler plugin data type. Try to avoid
constructing one of these directly, and just modify some fields of
defaultPlugin
instead: this is to try and preserve source-code
compatibility when we add fields to this.
Nonetheless, this API is preliminary and highly likely to change in the future.
TyCons represent type constructors. Type constructors are introduced by things such as:
1) Data declarations: data Foo = ...
creates the Foo
type constructor of
kind *
2) Type synonyms: type Foo = ...
creates the Foo
type constructor
3) Newtypes: newtype Foo a = MkFoo ...
creates the Foo
type constructor
of kind * -> *
4) Class declarations: class Foo where
creates the Foo
type constructor
of kind *
This data type also encodes a number of primitive, built in type constructors such as those for function and tuple types.
Instances
Eq TyCon | |
Data TyCon | |
Defined in TyCon gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> TyCon -> c TyCon # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c TyCon # dataTypeOf :: TyCon -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c TyCon) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c TyCon) # gmapT :: (forall b. Data b => b -> b) -> TyCon -> TyCon # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> TyCon -> r # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> TyCon -> r # gmapQ :: (forall d. Data d => d -> u) -> TyCon -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> TyCon -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> TyCon -> m TyCon # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> TyCon -> m TyCon # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> TyCon -> m TyCon # | |
NamedThing TyCon | |
Uniquable TyCon | |
Outputable TyCon | |
Instances
Data Type | |
Defined in TyCoRep gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Type -> c Type # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Type # dataTypeOf :: Type -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Type) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Type) # gmapT :: (forall b. Data b => b -> b) -> Type -> Type # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Type -> r # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Type -> r # gmapQ :: (forall d. Data d => d -> u) -> Type -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Type -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Type -> m Type # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Type -> m Type # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Type -> m Type # | |
Outputable Type | |