License	BSD-style (see the LICENSE file in the distribution)
Maintainer	libraries@haskell.org
Stability	experimental
Portability	not portable
Safe Haskell	None
Language	Haskell2010

Data.Type.Coercion

Description

Definition of representational equality (Coercion).

Since: 4.7.0.0

Synopsis

dataCoercion a bwhere
- Coercion ::Coercible a b =>Coercion a b
coerceWith ::Coercion a b -> a -> b
gcoerceWith ::Coercion a b -> (Coercible a b => r) -> r
sym ::Coercion a b ->Coercion b a
trans ::Coercion a b ->Coercion b c ->Coercion a c
repr :: (a:~: b) ->Coercion a b
classTestCoercion fwhere
- testCoercion :: f a -> f b ->Maybe (Coercion a b)

Documentation

dataCoercion a bwhereSource #

Representational equality. IfCoercion a b is inhabited by some terminating value, then the typea has the same underlying representation as the typeb.

To use this equality in practice, pattern-match on theCoercion a b to get out theCoercible a b instance, and then usecoerce to apply it.

Since: 4.7.0.0

Constructors

Coercion ::Coercible a b =>Coercion a b

Instances

Category (Coercion :: k -> k ->Type)Source #	Since: 4.7.0.0
Instance details Defined inControl.Category Methods id ::Coercion a aSource # (.) ::Coercion b c ->Coercion a b ->Coercion a cSource #
TestCoercion (Coercion a :: k ->Type)Source #	Since: 4.7.0.0
Instance details Defined inData.Type.Coercion Methods testCoercion ::Coercion a a0 ->Coercion a b ->Maybe (Coercion a0 b)Source #
Coercible a b =>Bounded (Coercion a b)Source #	Since: 4.7.0.0
Instance details Defined inData.Type.Coercion Methods minBound ::Coercion a bSource # maxBound ::Coercion a bSource #
Coercible a b =>Enum (Coercion a b)Source #	Since: 4.7.0.0
Instance details Defined inData.Type.Coercion Methods succ ::Coercion a b ->Coercion a bSource # pred ::Coercion a b ->Coercion a bSource # toEnum ::Int ->Coercion a bSource # fromEnum ::Coercion a b ->Int Source # enumFrom ::Coercion a b -> [Coercion a b]Source # enumFromThen ::Coercion a b ->Coercion a b -> [Coercion a b]Source # enumFromTo ::Coercion a b ->Coercion a b -> [Coercion a b]Source # enumFromThenTo ::Coercion a b ->Coercion a b ->Coercion a b -> [Coercion a b]Source #
Eq (Coercion a b)Source #	Since: 4.7.0.0
Instance details Defined inData.Type.Coercion Methods (==) ::Coercion a b ->Coercion a b ->Bool # (/=) ::Coercion a b ->Coercion a b ->Bool #
(Coercible a b,Data a,Data b) =>Data (Coercion a b)Source #	Since: 4.7.0.0
Instance details Defined inData.Data Methods gfoldl :: (forall d b0.Data d => c (d -> b0) -> d -> c b0) -> (forall g. g -> c g) ->Coercion a b -> c (Coercion a b)Source # gunfold :: (forall b0 r.Data b0 => c (b0 -> r) -> c r) -> (forall r. r -> c r) ->Constr -> c (Coercion a b)Source # toConstr ::Coercion a b ->Constr Source # dataTypeOf ::Coercion a b ->DataType Source # dataCast1 ::Typeable t => (forall d.Data d => c (t d)) ->Maybe (c (Coercion a b))Source # dataCast2 ::Typeable t => (forall d e. (Data d,Data e) => c (t d e)) ->Maybe (c (Coercion a b))Source # gmapT :: (forall b0.Data b0 => b0 -> b0) ->Coercion a b ->Coercion a bSource # gmapQl :: (r -> r' -> r) -> r -> (forall d.Data d => d -> r') ->Coercion a b -> rSource # gmapQr :: (r' -> r -> r) -> r -> (forall d.Data d => d -> r') ->Coercion a b -> rSource # gmapQ :: (forall d.Data d => d -> u) ->Coercion a b -> [u]Source # gmapQi ::Int -> (forall d.Data d => d -> u) ->Coercion a b -> uSource # gmapM ::Monad m => (forall d.Data d => d -> m d) ->Coercion a b -> m (Coercion a b)Source # gmapMp ::MonadPlus m => (forall d.Data d => d -> m d) ->Coercion a b -> m (Coercion a b)Source # gmapMo ::MonadPlus m => (forall d.Data d => d -> m d) ->Coercion a b -> m (Coercion a b)Source #
Ord (Coercion a b)Source #	Since: 4.7.0.0
Instance details Defined inData.Type.Coercion Methods compare ::Coercion a b ->Coercion a b ->Ordering # (<) ::Coercion a b ->Coercion a b ->Bool # (<=) ::Coercion a b ->Coercion a b ->Bool # (>) ::Coercion a b ->Coercion a b ->Bool # (>=) ::Coercion a b ->Coercion a b ->Bool # max ::Coercion a b ->Coercion a b ->Coercion a b# min ::Coercion a b ->Coercion a b ->Coercion a b#
Coercible a b =>Read (Coercion a b)Source #	Since: 4.7.0.0
Instance details Defined inData.Type.Coercion Methods readsPrec ::Int ->ReadS (Coercion a b)Source # readList ::ReadS [Coercion a b]Source # readPrec ::ReadPrec (Coercion a b)Source # readListPrec ::ReadPrec [Coercion a b]Source #
Show (Coercion a b)Source #	Since: 4.7.0.0
Instance details Defined inData.Type.Coercion Methods showsPrec ::Int ->Coercion a b ->ShowS Source # show ::Coercion a b ->String Source # showList :: [Coercion a b] ->ShowS Source #

coerceWith ::Coercion a b -> a -> bSource #

Type-safe cast, using representational equality

gcoerceWith ::Coercion a b -> (Coercible a b => r) -> rSource #

Generalized form of type-safe cast using representational equality

Since: 4.10.0.0

sym ::Coercion a b ->Coercion b aSource #

Symmetry of representational equality

trans ::Coercion a b ->Coercion b c ->Coercion a cSource #

Transitivity of representational equality

repr :: (a:~: b) ->Coercion a bSource #

Convert propositional (nominal) equality to representational equality

classTestCoercion fwhereSource #

This class contains types where you can learn the equality of two types from information contained interms. Typically, only singleton types should inhabit this class.

Methods

testCoercion :: f a -> f b ->Maybe (Coercion a b)Source #

Conditionally prove the representational equality ofa andb.

Instances

TestCoercion (Coercion a :: k ->Type)Source #	Since: 4.7.0.0
Instance details Defined inData.Type.Coercion Methods testCoercion ::Coercion a a0 ->Coercion a b ->Maybe (Coercion a0 b)Source #
TestCoercion ((:~:) a :: k ->Type)Source #	Since: 4.7.0.0
Instance details Defined inData.Type.Coercion Methods testCoercion :: (a:~: a0) -> (a:~: b) ->Maybe (Coercion a0 b)Source #
TestCoercion ((:~~:) a :: k ->Type)Source #	Since: 4.10.0.0
Instance details Defined inData.Type.Coercion Methods testCoercion :: (a:~~: a0) -> (a:~~: b) ->Maybe (Coercion a0 b)Source #

Movatterモバイル変換

Documentation