Data.Typeable

The Typeable class reifies types to some extent by associating type representations to types. These type representations can be compared, and one can in turn define a type-safe cast operation. To this end, an unsafe cast is guarded by a test for type (representation) equivalence. The module Data.Dynamic uses Typeable for an implementation of dynamics. The module Data.Data uses Typeable and type-safe cast (but not dynamics) to support the "Scrap your boilerplate" style of generic programming.

Compatibility Notes

Since GHC 8.2, GHC has supported type-indexed type representations. Data.Typeable provides type representations which are qualified over this index, providing an interface very similar to the Typeable notion seen in previous releases. For the type-indexed interface, see Type.Reflection.

Since GHC 7.10, all types automatically have Typeable instances derived. This is in contrast to previous releases where Typeable had to be explicitly derived using the DeriveDataTypeable language extension.

Since GHC 7.8, Typeable is poly-kinded. The changes required for this might break some old programs involving Typeable. More details on this, including how to fix your code, can be found on the PolyTypeable wiki page

The Typeable class

class Typeable (a :: k)

The class Typeable allows a concrete representation of a type to be calculated.

Minimal complete definition

typeRep#

typeOf :: Typeable a => a -> TypeRep

Observe a type representation for the type of a value.

typeRep :: forall {k} proxy (a :: k). Typeable a => proxy a -> TypeRep

Takes a value of type a and returns a concrete representation of that type.

Since: base-4.7.0.0

Propositional equality

data (a :: k) :~: (b :: k) where infix 4

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: base-4.7.0.0

Constructors

Refl :: forall {k} (a :: k). a :~: a

Instances

Category ((:~:) :: k -> k -> Type)

Since: base-4.7.0.0

Defined in GHC.Internal.Control.Category

Methods

id :: forall (a :: k). a :~: a

(.) :: forall (b :: k) (c :: k) (a :: k). (b :~: c) -> (a :~: b) -> a :~: c

TestCoercion ((:~:) a :: k -> Type)

Since: base-4.7.0.0

Defined in GHC.Internal.Data.Type.Coercion

Methods

testCoercion :: forall (a0 :: k) (b :: k). (a :~: a0) -> (a :~: b) -> Maybe (Coercion a0 b)

TestEquality ((:~:) a :: k -> Type)

Since: base-4.7.0.0

Defined in GHC.Internal.Data.Type.Equality

Methods

testEquality :: forall (a0 :: k) (b :: k). (a :~: a0) -> (a :~: b) -> Maybe (a0 :~: b)

(a ~ b, Data a) => Data (a :~: b)

Since: base-4.7.0.0

Defined in GHC.Internal.Data.Data

Methods

gfoldl :: (forall d b0. Data d => c (d -> b0) -> d -> c b0) -> (forall g. g -> c g) -> (a :~: b) -> c (a :~: b)

gunfold :: (forall b0 r. Data b0 => c (b0 -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (a :~: b)

toConstr :: (a :~: b) -> Constr

dataTypeOf :: (a :~: b) -> DataType

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (a :~: b))

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (a :~: b))

gmapT :: (forall b0. Data b0 => b0 -> b0) -> (a :~: b) -> a :~: b

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> (a :~: b) -> r

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> (a :~: b) -> r

gmapQ :: (forall d. Data d => d -> u) -> (a :~: b) -> [u]

gmapQi :: Int -> (forall d. Data d => d -> u) -> (a :~: b) -> u

gmapM :: Monad m => (forall d. Data d => d -> m d) -> (a :~: b) -> m (a :~: b)

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> (a :~: b) -> m (a :~: b)

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> (a :~: b) -> m (a :~: b)

a ~ b => Bounded (a :~: b)

Since: base-4.7.0.0

Defined in GHC.Internal.Data.Type.Equality

Methods

minBound :: a :~: b

maxBound :: a :~: b

a ~ b => Enum (a :~: b)

Since: base-4.7.0.0

Defined in GHC.Internal.Data.Type.Equality

Methods

succ :: (a :~: b) -> a :~: b

pred :: (a :~: b) -> a :~: b

toEnum :: Int -> a :~: b

fromEnum :: (a :~: b) -> Int

enumFrom :: (a :~: b) -> [a :~: b]

enumFromThen :: (a :~: b) -> (a :~: b) -> [a :~: b]

enumFromTo :: (a :~: b) -> (a :~: b) -> [a :~: b]

enumFromThenTo :: (a :~: b) -> (a :~: b) -> (a :~: b) -> [a :~: b]

a ~ b => Read (a :~: b)

Since: base-4.7.0.0

Defined in GHC.Internal.Data.Type.Equality

Methods

readsPrec :: Int -> ReadS (a :~: b)

readList :: ReadS [a :~: b]

readPrec :: ReadPrec (a :~: b)

readListPrec :: ReadPrec [a :~: b]

Show (a :~: b)

Since: base-4.7.0.0

Defined in GHC.Internal.Data.Type.Equality

Methods

showsPrec :: Int -> (a :~: b) -> ShowS

show :: (a :~: b) -> String

showList :: [a :~: b] -> ShowS

Eq (a :~: b)

Since: base-4.7.0.0

Defined in GHC.Internal.Data.Type.Equality

Methods

(==) :: (a :~: b) -> (a :~: b) -> Bool

(/=) :: (a :~: b) -> (a :~: b) -> Bool

Ord (a :~: b)

Since: base-4.7.0.0

Defined in GHC.Internal.Data.Type.Equality

Methods

compare :: (a :~: b) -> (a :~: b) -> Ordering

(<) :: (a :~: b) -> (a :~: b) -> Bool

(<=) :: (a :~: b) -> (a :~: b) -> Bool

(>) :: (a :~: b) -> (a :~: b) -> Bool

(>=) :: (a :~: b) -> (a :~: b) -> Bool

max :: (a :~: b) -> (a :~: b) -> a :~: b

min :: (a :~: b) -> (a :~: b) -> a :~: b

data (a :: k1) :~~: (b :: k2) where infix 4

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: base-4.10.0.0

Constructors

HRefl :: forall {k1} (a :: k1). a :~~: a

Instances

Category ((:~~:) :: k -> k -> Type)

Since: base-4.10.0.0

Defined in GHC.Internal.Control.Category

Methods

id :: forall (a :: k). a :~~: a

(.) :: forall (b :: k) (c :: k) (a :: k). (b :~~: c) -> (a :~~: b) -> a :~~: c

TestCoercion ((:~~:) a :: k -> Type)

Since: base-4.10.0.0

Defined in GHC.Internal.Data.Type.Coercion

Methods

testCoercion :: forall (a0 :: k) (b :: k). (a :~~: a0) -> (a :~~: b) -> Maybe (Coercion a0 b)

TestEquality ((:~~:) a :: k -> Type)

Since: base-4.10.0.0

Defined in GHC.Internal.Data.Type.Equality

Methods

testEquality :: forall (a0 :: k) (b :: k). (a :~~: a0) -> (a :~~: b) -> Maybe (a0 :~: b)

(Typeable i, Typeable j, Typeable a, Typeable b, a ~~ b) => Data (a :~~: b)

Since: base-4.10.0.0

Defined in GHC.Internal.Data.Data

Methods

gfoldl :: (forall d b0. Data d => c (d -> b0) -> d -> c b0) -> (forall g. g -> c g) -> (a :~~: b) -> c (a :~~: b)

gunfold :: (forall b0 r. Data b0 => c (b0 -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (a :~~: b)

toConstr :: (a :~~: b) -> Constr

dataTypeOf :: (a :~~: b) -> DataType

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (a :~~: b))

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (a :~~: b))

gmapT :: (forall b0. Data b0 => b0 -> b0) -> (a :~~: b) -> a :~~: b

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> (a :~~: b) -> r

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> (a :~~: b) -> r

gmapQ :: (forall d. Data d => d -> u) -> (a :~~: b) -> [u]

gmapQi :: Int -> (forall d. Data d => d -> u) -> (a :~~: b) -> u

gmapM :: Monad m => (forall d. Data d => d -> m d) -> (a :~~: b) -> m (a :~~: b)

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> (a :~~: b) -> m (a :~~: b)

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> (a :~~: b) -> m (a :~~: b)

a ~~ b => Bounded (a :~~: b)

Since: base-4.10.0.0

Defined in GHC.Internal.Data.Type.Equality

Methods

minBound :: a :~~: b

maxBound :: a :~~: b

a ~~ b => Enum (a :~~: b)

Since: base-4.10.0.0

Defined in GHC.Internal.Data.Type.Equality

Methods

succ :: (a :~~: b) -> a :~~: b

pred :: (a :~~: b) -> a :~~: b

toEnum :: Int -> a :~~: b

fromEnum :: (a :~~: b) -> Int

enumFrom :: (a :~~: b) -> [a :~~: b]

enumFromThen :: (a :~~: b) -> (a :~~: b) -> [a :~~: b]

enumFromTo :: (a :~~: b) -> (a :~~: b) -> [a :~~: b]

enumFromThenTo :: (a :~~: b) -> (a :~~: b) -> (a :~~: b) -> [a :~~: b]

a ~~ b => Read (a :~~: b)

Since: base-4.10.0.0

Defined in GHC.Internal.Data.Type.Equality

Methods

readsPrec :: Int -> ReadS (a :~~: b)

readList :: ReadS [a :~~: b]

readPrec :: ReadPrec (a :~~: b)

readListPrec :: ReadPrec [a :~~: b]

Show (a :~~: b)

Since: base-4.10.0.0

Defined in GHC.Internal.Data.Type.Equality

Methods

showsPrec :: Int -> (a :~~: b) -> ShowS

show :: (a :~~: b) -> String

showList :: [a :~~: b] -> ShowS

Eq (a :~~: b)

Since: base-4.10.0.0

Defined in GHC.Internal.Data.Type.Equality

Methods

(==) :: (a :~~: b) -> (a :~~: b) -> Bool

(/=) :: (a :~~: b) -> (a :~~: b) -> Bool

Ord (a :~~: b)

Since: base-4.10.0.0

Defined in GHC.Internal.Data.Type.Equality

Methods

compare :: (a :~~: b) -> (a :~~: b) -> Ordering

(<) :: (a :~~: b) -> (a :~~: b) -> Bool

(<=) :: (a :~~: b) -> (a :~~: b) -> Bool

(>) :: (a :~~: b) -> (a :~~: b) -> Bool

(>=) :: (a :~~: b) -> (a :~~: b) -> Bool

max :: (a :~~: b) -> (a :~~: b) -> a :~~: b

min :: (a :~~: b) -> (a :~~: b) -> a :~~: b

Type-safe cast

cast :: (Typeable a, Typeable b) => a -> Maybe b

The type-safe cast operation

eqT :: forall {k} (a :: k) (b :: k). (Typeable a, Typeable b) => Maybe (a :~: b)

Extract a witness of equality of two types

Since: base-4.7.0.0

heqT :: forall {k1} {k2} (a :: k1) (b :: k2). (Typeable a, Typeable b) => Maybe (a :~~: b)

Extract a witness of heterogeneous equality of two types

Since: base-4.18.0.0

decT :: forall {k} (a :: k) (b :: k). (Typeable a, Typeable b) => Either ((a :~: b) -> Void) (a :~: b)

Decide an equality of two types

Since: base-4.19.0.0

hdecT :: forall {k1} {k2} (a :: k1) (b :: k2). (Typeable a, Typeable b) => Either ((a :~~: b) -> Void) (a :~~: b)

Decide heterogeneous equality of two types.

Since: base-4.19.0.0

gcast :: forall {k} (a :: k) (b :: k) c. (Typeable a, Typeable b) => c a -> Maybe (c b)

A flexible variation parameterised in a type constructor

Generalized casts for higher-order kinds

gcast1 :: forall {k1} {k2} c (t :: k2 -> k1) (t' :: k2 -> k1) (a :: k2). (Typeable t, Typeable t') => c (t a) -> Maybe (c (t' a))

Cast over k1 -> k2

gcast2 :: forall {k1} {k2} {k3} c (t :: k2 -> k3 -> k1) (t' :: k2 -> k3 -> k1) (a :: k2) (b :: k3). (Typeable t, Typeable t') => c (t a b) -> Maybe (c (t' a b))

Cast over k1 -> k2 -> k3

A canonical proxy type

data Proxy (t :: k)

Proxy is a type that holds no data, but has a phantom parameter of arbitrary type (or even kind). Its use is to provide type information, even though there is no value available of that type (or it may be too costly to create one).

Historically, Proxy :: Proxy a is a safer alternative to the undefined :: a idiom.

>>> Proxy :: Proxy (Void, Int -> Int)
Proxy

Proxy can even hold types of higher kinds,

>>> Proxy :: Proxy Either
Proxy

>>> Proxy :: Proxy Functor
Proxy

>>> Proxy :: Proxy complicatedStructure
Proxy

Constructors

Proxy

Instances

Generic1 (Proxy :: k -> Type)

Defined in GHC.Internal.Generics

Associated Types

type Rep1 (Proxy :: k -> Type)

Since: base-4.6.0.0

Defined in GHC.Internal.Generics

type Rep1 (Proxy :: k -> Type) = D1 ('MetaData "Proxy" "GHC.Internal.Data.Proxy" "ghc-internal" 'False) (C1 ('MetaCons "Proxy" 'PrefixI 'False) (U1 :: k -> Type))

Methods

from1 :: forall (a :: k). Proxy a -> Rep1 (Proxy :: k -> Type) a

to1 :: forall (a :: k). Rep1 (Proxy :: k -> Type) a -> Proxy a

MonadZip (Proxy :: Type -> Type)

Since: base-4.9.0.0

Defined in Control.Monad.Zip

Methods

mzip :: Proxy a -> Proxy b -> Proxy (a, b)

mzipWith :: (a -> b -> c) -> Proxy a -> Proxy b -> Proxy c

munzip :: Proxy (a, b) -> (Proxy a, Proxy b)

Eq1 (Proxy :: Type -> Type)

Since: base-4.9.0.0

Defined in Data.Functor.Classes

Methods

liftEq :: (a -> b -> Bool) -> Proxy a -> Proxy b -> Bool

Ord1 (Proxy :: Type -> Type)

Since: base-4.9.0.0

Defined in Data.Functor.Classes

Methods

liftCompare :: (a -> b -> Ordering) -> Proxy a -> Proxy b -> Ordering

Read1 (Proxy :: Type -> Type)

Since: base-4.9.0.0

Defined in Data.Functor.Classes

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (Proxy a)

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [Proxy a]

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (Proxy a)

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [Proxy a]

Show1 (Proxy :: Type -> Type)

Since: base-4.9.0.0

Defined in Data.Functor.Classes

Methods

liftShowsPrec :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> Int -> Proxy a -> ShowS

liftShowList :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> [Proxy a] -> ShowS

Contravariant (Proxy :: Type -> Type)

Defined in Data.Functor.Contravariant

Methods

contramap :: (a' -> a) -> Proxy a -> Proxy a'

(>$) :: b -> Proxy b -> Proxy a

Alternative (Proxy :: Type -> Type)

Since: base-4.9.0.0

Defined in GHC.Internal.Data.Proxy

Methods

empty :: Proxy a

(<|>) :: Proxy a -> Proxy a -> Proxy a

some :: Proxy a -> Proxy [a]

many :: Proxy a -> Proxy [a]

Applicative (Proxy :: Type -> Type)

Since: base-4.7.0.0

Defined in GHC.Internal.Data.Proxy

Methods

pure :: a -> Proxy a

(<*>) :: Proxy (a -> b) -> Proxy a -> Proxy b

liftA2 :: (a -> b -> c) -> Proxy a -> Proxy b -> Proxy c

(*>) :: Proxy a -> Proxy b -> Proxy b

(<*) :: Proxy a -> Proxy b -> Proxy a

Functor (Proxy :: Type -> Type)

Since: base-4.7.0.0

Defined in GHC.Internal.Data.Proxy

Methods

fmap :: (a -> b) -> Proxy a -> Proxy b

(<$) :: a -> Proxy b -> Proxy a

Monad (Proxy :: Type -> Type)

Since: base-4.7.0.0

Defined in GHC.Internal.Data.Proxy

Methods

(>>=) :: Proxy a -> (a -> Proxy b) -> Proxy b

(>>) :: Proxy a -> Proxy b -> Proxy b

return :: a -> Proxy a

MonadPlus (Proxy :: Type -> Type)

Since: base-4.9.0.0

Defined in GHC.Internal.Data.Proxy

Methods

mzero :: Proxy a

mplus :: Proxy a -> Proxy a -> Proxy a

Foldable (Proxy :: Type -> Type)

Since: base-4.7.0.0

Defined in GHC.Internal.Data.Foldable

Methods

fold :: Monoid m => Proxy m -> m

foldMap :: Monoid m => (a -> m) -> Proxy a -> m

foldMap' :: Monoid m => (a -> m) -> Proxy a -> m

foldr :: (a -> b -> b) -> b -> Proxy a -> b

foldr' :: (a -> b -> b) -> b -> Proxy a -> b

foldl :: (b -> a -> b) -> b -> Proxy a -> b

foldl' :: (b -> a -> b) -> b -> Proxy a -> b

foldr1 :: (a -> a -> a) -> Proxy a -> a

foldl1 :: (a -> a -> a) -> Proxy a -> a

toList :: Proxy a -> [a]

null :: Proxy a -> Bool

length :: Proxy a -> Int

elem :: Eq a => a -> Proxy a -> Bool

maximum :: Ord a => Proxy a -> a

minimum :: Ord a => Proxy a -> a

sum :: Num a => Proxy a -> a

product :: Num a => Proxy a -> a

Traversable (Proxy :: Type -> Type)

Since: base-4.7.0.0

Defined in GHC.Internal.Data.Traversable

Methods

traverse :: Applicative f => (a -> f b) -> Proxy a -> f (Proxy b)

sequenceA :: Applicative f => Proxy (f a) -> f (Proxy a)

mapM :: Monad m => (a -> m b) -> Proxy a -> m (Proxy b)

sequence :: Monad m => Proxy (m a) -> m (Proxy a)

Monoid (Proxy s)

Since: base-4.7.0.0

Defined in GHC.Internal.Data.Proxy

Methods

mempty :: Proxy s

mappend :: Proxy s -> Proxy s -> Proxy s

mconcat :: [Proxy s] -> Proxy s

Semigroup (Proxy s)

Since: base-4.9.0.0

Defined in GHC.Internal.Data.Proxy

Methods

(<>) :: Proxy s -> Proxy s -> Proxy s

sconcat :: NonEmpty (Proxy s) -> Proxy s

stimes :: Integral b => b -> Proxy s -> Proxy s

Data t => Data (Proxy t)

Since: base-4.7.0.0

Defined in GHC.Internal.Data.Data

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Proxy t -> c (Proxy t)

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Proxy t)

toConstr :: Proxy t -> Constr

dataTypeOf :: Proxy t -> DataType

dataCast1 :: Typeable t0 => (forall d. Data d => c (t0 d)) -> Maybe (c (Proxy t))

dataCast2 :: Typeable t0 => (forall d e. (Data d, Data e) => c (t0 d e)) -> Maybe (c (Proxy t))

gmapT :: (forall b. Data b => b -> b) -> Proxy t -> Proxy t

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Proxy t -> r

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Proxy t -> r

gmapQ :: (forall d. Data d => d -> u) -> Proxy t -> [u]

gmapQi :: Int -> (forall d. Data d => d -> u) -> Proxy t -> u

gmapM :: Monad m => (forall d. Data d => d -> m d) -> Proxy t -> m (Proxy t)

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Proxy t -> m (Proxy t)

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Proxy t -> m (Proxy t)

Bounded (Proxy t)

Since: base-4.7.0.0

Defined in GHC.Internal.Data.Proxy

Methods

minBound :: Proxy t

maxBound :: Proxy t

Enum (Proxy s)

Since: base-4.7.0.0

Defined in GHC.Internal.Data.Proxy

Methods

succ :: Proxy s -> Proxy s

pred :: Proxy s -> Proxy s

toEnum :: Int -> Proxy s

fromEnum :: Proxy s -> Int

enumFrom :: Proxy s -> [Proxy s]

enumFromThen :: Proxy s -> Proxy s -> [Proxy s]

enumFromTo :: Proxy s -> Proxy s -> [Proxy s]

enumFromThenTo :: Proxy s -> Proxy s -> Proxy s -> [Proxy s]

Generic (Proxy t)

Defined in GHC.Internal.Generics

Associated Types

type Rep (Proxy t)

Since: base-4.6.0.0

Defined in GHC.Internal.Generics

type Rep (Proxy t) = D1 ('MetaData "Proxy" "GHC.Internal.Data.Proxy" "ghc-internal" 'False) (C1 ('MetaCons "Proxy" 'PrefixI 'False) (U1 :: Type -> Type))

Methods

from :: Proxy t -> Rep (Proxy t) x

to :: Rep (Proxy t) x -> Proxy t

Ix (Proxy s)

Since: base-4.7.0.0

Defined in GHC.Internal.Data.Proxy

Methods

range :: (Proxy s, Proxy s) -> [Proxy s]

index :: (Proxy s, Proxy s) -> Proxy s -> Int

unsafeIndex :: (Proxy s, Proxy s) -> Proxy s -> Int

inRange :: (Proxy s, Proxy s) -> Proxy s -> Bool

rangeSize :: (Proxy s, Proxy s) -> Int

unsafeRangeSize :: (Proxy s, Proxy s) -> Int

Read (Proxy t)

Since: base-4.7.0.0

Defined in GHC.Internal.Data.Proxy

Methods

readsPrec :: Int -> ReadS (Proxy t)

readList :: ReadS [Proxy t]

readPrec :: ReadPrec (Proxy t)

readListPrec :: ReadPrec [Proxy t]

Show (Proxy s)

Since: base-4.7.0.0

Defined in GHC.Internal.Data.Proxy

Methods

showsPrec :: Int -> Proxy s -> ShowS

show :: Proxy s -> String

showList :: [Proxy s] -> ShowS

Eq (Proxy s)

Since: base-4.7.0.0

Defined in GHC.Internal.Data.Proxy

Methods

(==) :: Proxy s -> Proxy s -> Bool

(/=) :: Proxy s -> Proxy s -> Bool

Ord (Proxy s)

Since: base-4.7.0.0

Defined in GHC.Internal.Data.Proxy

Methods

compare :: Proxy s -> Proxy s -> Ordering

(<) :: Proxy s -> Proxy s -> Bool

(<=) :: Proxy s -> Proxy s -> Bool

(>) :: Proxy s -> Proxy s -> Bool

(>=) :: Proxy s -> Proxy s -> Bool

max :: Proxy s -> Proxy s -> Proxy s

min :: Proxy s -> Proxy s -> Proxy s

type Rep1 (Proxy :: k -> Type)

Since: base-4.6.0.0

Defined in GHC.Internal.Generics

type Rep1 (Proxy :: k -> Type) = D1 ('MetaData "Proxy" "GHC.Internal.Data.Proxy" "ghc-internal" 'False) (C1 ('MetaCons "Proxy" 'PrefixI 'False) (U1 :: k -> Type))

type Rep (Proxy t)

Since: base-4.6.0.0

Defined in GHC.Internal.Generics

type Rep (Proxy t) = D1 ('MetaData "Proxy" "GHC.Internal.Data.Proxy" "ghc-internal" 'False) (C1 ('MetaCons "Proxy" 'PrefixI 'False) (U1 :: Type -> Type))

Type representations

type TypeRep = SomeTypeRep

A quantified type representation.

rnfTypeRep :: TypeRep -> ()

Force a TypeRep to normal form.

showsTypeRep :: TypeRep -> ShowS

Show a type representation

mkFunTy :: TypeRep -> TypeRep -> TypeRep

Build a function type.

Observing type representations

funResultTy :: TypeRep -> TypeRep -> Maybe TypeRep

Applies a type to a function type. Returns: Just u if the first argument represents a function of type t -> u and the second argument represents a function of type t. Otherwise, returns Nothing.

splitTyConApp :: TypeRep -> (TyCon, [TypeRep])

Splits a type constructor application. Note that if the type constructor is polymorphic, this will not return the kinds that were used.

typeRepArgs :: TypeRep -> [TypeRep]

Observe the argument types of a type representation

typeRepTyCon :: TypeRep -> TyCon

Observe the type constructor of a quantified type representation.

typeRepFingerprint :: TypeRep -> Fingerprint

Takes a value of type a and returns a concrete representation of that type.

Since: base-4.7.0.0

Type constructors

data TyCon

Instances

Show TyCon

Since: base-2.1

Defined in GHC.Internal.Show

Methods

showsPrec :: Int -> TyCon -> ShowS

show :: TyCon -> String

showList :: [TyCon] -> ShowS

Eq TyCon

Defined in GHC.Classes

Methods

(==) :: TyCon -> TyCon -> Bool

(/=) :: TyCon -> TyCon -> Bool

Ord TyCon

Defined in GHC.Classes

Methods

compare :: TyCon -> TyCon -> Ordering

(<) :: TyCon -> TyCon -> Bool

(<=) :: TyCon -> TyCon -> Bool

(>) :: TyCon -> TyCon -> Bool

(>=) :: TyCon -> TyCon -> Bool

max :: TyCon -> TyCon -> TyCon

min :: TyCon -> TyCon -> TyCon

tyConPackage :: TyCon -> String

tyConModule :: TyCon -> String

tyConName :: TyCon -> String

rnfTyCon :: TyCon -> ()

tyConFingerprint :: TyCon -> Fingerprint

For backwards compatibility

typeOf1 :: Typeable t => t a -> TypeRep

typeOf2 :: Typeable t => t a b -> TypeRep

typeOf3 :: Typeable t => t a b c -> TypeRep

typeOf4 :: Typeable t => t a b c d -> TypeRep

typeOf5 :: Typeable t => t a b c d e -> TypeRep

typeOf6 :: Typeable t => t a b c d e f -> TypeRep

typeOf7 :: Typeable t => t a b c d e f g -> TypeRep

trLiftedRep :: TypeRep LiftedRep