Copyright | (c) The University of Glasgow CWI 2001--2017 |
---|---|
License | BSD-style (see the file libraries/base/LICENSE) |
Maintainer | [email protected] |
Stability | experimental |
Portability | non-portable (requires GADTs and compiler support) |
Safe Haskell | Trustworthy |
Language | Haskell2010 |
This provides a type-indexed type representation mechanism, similar to that described by,
The interface provides TypeRep
, a type representation which can be safely decomposed and composed. See Data.Dynamic for an example of this.
Since: 4.10.0.0
class Typeable (a :: k) Source
The class Typeable
allows a concrete representation of a type to be calculated.
typeRep#
typeRep :: Typeable a => TypeRep a Source
withTypeable :: forall a r. TypeRep a -> (Typeable a => r) -> r Source
Use a TypeRep
as Typeable
evidence.
data a :~: b where infix 4 Source
Propositional equality. If a :~: b
is inhabited by some terminating value, then the type a
is the same as the type b
. To use this equality in practice, pattern-match on the a :~: b
to get out the Refl
constructor; in the body of the pattern-match, the compiler knows that a ~ b
.
Since: 4.7.0.0
Category k ((:~:) k) | Since: 4.7.0.0 |
TestEquality k ((:~:) k a) | Since: 4.7.0.0 |
TestCoercion k ((:~:) k a) | Since: 4.7.0.0 |
(~) k a b => Bounded ((:~:) k a b) | Since: 4.7.0.0 |
(~) k a b => Enum ((:~:) k a b) | Since: 4.7.0.0 |
Eq ((:~:) k a b) | |
((~) * a b, Data a) => Data ((:~:) * a b) | Since: 4.7.0.0 |
Ord ((:~:) k a b) | |
(~) k a b => Read ((:~:) k a b) | Since: 4.7.0.0 |
Show ((:~:) k a b) | |
data (a :: k1) :~~: (b :: k2) where infix 4 Source
Kind heterogeneous propositional equality. Like '(:~:)', a :~~: b
is inhabited by a terminating value if and only if a
is the same type as b
.
Since: 4.10.0.0
Category k ((:~~:) k k) | Since: 4.10.0.0 |
TestEquality k ((:~~:) k1 k a) | Since: 4.10.0.0 |
TestCoercion k ((:~~:) k1 k a) | Since: 4.10.0.0 |
(~~) k1 k2 a b => Bounded ((:~~:) k1 k2 a b) | Since: 4.10.0.0 |
(~~) k1 k2 a b => Enum ((:~~:) k1 k2 a b) | Since: 4.10.0.0 |
Eq ((:~~:) k1 k2 a b) | Since: 4.10.0.0 |
(Typeable * i2, Typeable * j2, Typeable i2 a, Typeable j2 b, (~~) i2 j2 a b) => Data ((:~~:) i2 j2 a b) | Since: 4.10.0.0 |
Ord ((:~~:) k1 k2 a b) | Since: 4.10.0.0 |
(~~) k1 k2 a b => Read ((:~~:) k1 k2 a b) | Since: 4.10.0.0 |
Show ((:~~:) k1 k2 a b) | Since: 4.10.0.0 |
A concrete representation of a (monomorphic) type. TypeRep
supports reasonably efficient equality.
typeOf :: Typeable a => a -> TypeRep a Source
pattern App :: forall k2 (t :: k2). forall k1 (a :: k1 -> k2) (b :: k1). t ~ a b => TypeRep a -> TypeRep b -> TypeRep t Source
Pattern match on a type application
pattern Con :: forall k (a :: k). TyCon -> TypeRep a Source
Pattern match on a type constructor
pattern Con' :: forall k (a :: k). TyCon -> [SomeTypeRep] -> TypeRep a Source
Pattern match on a type constructor including its instantiated kind variables.
pattern Fun :: forall k (fun :: k). forall (r1 :: RuntimeRep) (r2 :: RuntimeRep) (arg :: TYPE r1) (res :: TYPE r2). (k ~ Type, fun ~~ (arg -> res)) => TypeRep arg -> TypeRep res -> TypeRep fun Source
typeRepTyCon :: TypeRep a -> TyCon Source
Observe the type constructor of a type representation
rnfTypeRep :: TypeRep a -> () Source
Helper to fully evaluate TypeRep
for use as NFData(rnf)
implementation
Since: 4.8.0.0
eqTypeRep :: forall k1 k2 (a :: k1) (b :: k2). TypeRep a -> TypeRep b -> Maybe (a :~~: b) Source
Type equality
Since: 4.10
typeRepKind :: TypeRep (a :: k) -> TypeRep k Source
Observe the kind of a type.
splitApps :: TypeRep a -> (TyCon, [SomeTypeRep]) Source
data SomeTypeRep where Source
A non-indexed type representation.
SomeTypeRep :: forall k (a :: k). !(TypeRep a) -> SomeTypeRep |
Eq SomeTypeRep | |
Ord SomeTypeRep | |
Show SomeTypeRep | Since: 4.10.0.0 |
someTypeRep :: forall proxy a. Typeable a => proxy a -> SomeTypeRep Source
Takes a value of type a
and returns a concrete representation of that type.
Since: 4.7.0.0
someTypeRepTyCon :: SomeTypeRep -> TyCon Source
Observe the type constructor of a quantified type representation.
rnfSomeTypeRep :: SomeTypeRep -> () Source
Helper to fully evaluate SomeTypeRep
for use as NFData(rnf)
implementation
Since: 4.10.0.0
tyConPackage :: TyCon -> String Source
tyConModule :: TyCon -> String Source
tyConName :: TyCon -> String Source
rnfTyCon :: TyCon -> () Source
moduleName :: Module -> String Source
modulePackage :: Module -> String Source
rnfModule :: Module -> () Source
Helper to fully evaluate TyCon
for use as NFData(rnf)
implementation
Since: 4.8.0.0
© The University of Glasgow and others
Licensed under a BSD-style license (see top of the page).
https://downloads.haskell.org/~ghc/8.2.1/docs/html/libraries/base-4.10.0.0/Type-Reflection.html