| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Data.Type.Role.Representational
Synopsis
- class (forall a b. Coercible a b => Coercible (f a) (f b)) => Representational (f :: k -> l)
- data Representation (f :: k -> l) where
- Representation :: Representational f => Representation f
- applyRepresentational :: Representation f -> Coercion f g -> Coercion a b -> Coercion (f a) (g b)
- class (forall a b. Coercible (f a) (f b) => a ~ b) => NonRepresentational (f :: k -> l)
- data NonRepresentation (f :: k -> l) where
- innerNonRepresentational :: NonRepresentation f -> Coercion (f a) (f b) -> a :~: b
Documentation
class (forall a b. Coercible a b => Coercible (f a) (f b)) => Representational (f :: k -> l) Source #
A constraint witnessing that the next argument of the type constructor of
the f type has representational (or phantom) type role.
For example Either and Either a both automatically become instances of
this class.
Instances
| (forall (a :: k) (b :: k). Coercible a b => Coercible (f a) (f b)) => Representational (f :: k -> l) Source # | |
Defined in Data.Type.Role.Representational | |
data Representation (f :: k -> l) where Source #
A datatype witness of the representational type role.
Constructors
| Representation :: Representational f => Representation f |
applyRepresentational :: Representation f -> Coercion f g -> Coercion a b -> Coercion (f a) (g b) Source #
Apply a coercion of a representable datatype to a coercion of its argument.
class (forall a b. Coercible (f a) (f b) => a ~ b) => NonRepresentational (f :: k -> l) Source #
A constraint witnessing that the next argument of the type constructor of
the f type has a non-representational (nominal) type role.
For example Map automatically becomes an instance of this class.
Instances
| (forall (a :: k) (b :: k). Coercible (f a) (f b) => a ~ b) => NonRepresentational (f :: k -> l) Source # | |
Defined in Data.Type.Role.Representational | |
data NonRepresentation (f :: k -> l) where Source #
A datatype witness of the non-representational type role.
Constructors
| NonRepresentation :: NonRepresentational f => NonRepresentation f |
innerNonRepresentational :: NonRepresentation f -> Coercion (f a) (f b) -> a :~: b Source #
Extract equality from coercibility of types in a non-representable position.