Copyright	(c) The University of Glasgow CWI 2001--2017
License	BSD-style (see the file libraries/base/LICENSE)
Maintainer	libraries@haskell.org
Stability	experimental
Portability	non-portable (requires GADTs and compiler support)
Safe Haskell	Trustworthy
Language	Haskell2010

Type.Reflection

Contents

Description

This provides a type-indexed type representation mechanism, similar to that described by,

Simon Peyton-Jones, Stephanie Weirich, Richard Eisenberg, Dimitrios Vytiniotis. "A reflection on types." /Proc. Philip Wadler's 60th birthday Festschrift/, Edinburgh (April 2016).

The interface providesTypeRep, a type representation which can be safely decomposed and composed. SeeData.Dynamic for an example of this.

Since: 4.10.0.0

Synopsis

classTypeable (a :: k)
typeRep ::Typeable a =>TypeRep a
withTypeable ::forall k (a :: k) rep (r ::TYPE rep).TypeRep a -> (Typeable a => r) -> r
data a:~: bwhere
- Refl :: a:~: a
data (a :: k1):~~: (b :: k2)where
- HRefl :: a:~~: a
dataTypeRep (a :: k)
typeOf ::Typeable a => a ->TypeRep a
patternApp ::forall k2 (t :: k2). () =>forall k1 (a :: k1 -> k2) (b :: k1). t ~ a b =>TypeRep a ->TypeRep b ->TypeRep t
patternCon ::forall k (a :: k). () => IsApplication a ~ "" =>TyCon ->TypeRep a
patternCon' ::forall k (a :: k). () => IsApplication a ~ "" =>TyCon -> [SomeTypeRep] ->TypeRep a
patternFun ::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
typeRepTyCon ::TypeRep a ->TyCon
rnfTypeRep ::TypeRep a -> ()
eqTypeRep ::forall k1 k2 (a :: k1) (b :: k2).TypeRep a ->TypeRep b ->Maybe (a:~~: b)
typeRepKind ::TypeRep (a :: k) ->TypeRep k
splitApps ::TypeRep a -> (TyCon, [SomeTypeRep])
dataSomeTypeRepwhere
- SomeTypeRep ::forall k (a :: k). !(TypeRep a) ->SomeTypeRep
someTypeRep ::forall proxy a.Typeable a => proxy a ->SomeTypeRep
someTypeRepTyCon ::SomeTypeRep ->TyCon
rnfSomeTypeRep ::SomeTypeRep -> ()
dataTyCon
tyConPackage ::TyCon ->String
tyConModule ::TyCon ->String
tyConName ::TyCon ->String
rnfTyCon ::TyCon -> ()
dataModule
moduleName ::Module ->String
modulePackage ::Module ->String
rnfModule ::Module -> ()

The Typeable class

classTypeable (a :: k)Source #

The classTypeable allows a concrete representation of a type to be calculated.

Minimal complete definition

typeRep#

typeRep ::Typeable a =>TypeRep aSource #

withTypeable ::forall k (a :: k) rep (r ::TYPE rep).TypeRep a -> (Typeable a => r) -> rSource #

Use aTypeRep asTypeable evidence.

Propositional equality

data a:~: bwhereinfix 4Source #

Propositional equality. Ifa :~: b is inhabited by some terminating value, then the typea is the same as the typeb. To use this equality in practice, pattern-match on thea :~: b to get out theRefl constructor; in the body of the pattern-match, the compiler knows thata ~ b.

Since: 4.7.0.0

Constructors

Refl :: a:~: a

Instances

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

data (a :: k1):~~: (b :: k2)whereinfix 4Source #

Kind heterogeneous propositional equality. Like:~:,a :~~: b is inhabited by a terminating value if and only ifa is the same type asb.

Since: 4.10.0.0

Constructors

HRefl :: a:~~: a

Instances

Category ((:~~:) :: k -> k ->Type)Source #	Since: 4.10.0.0
Instance details Defined inControl.Category Methods id :: a:~~: aSource # (.) :: (b:~~: c) -> (a:~~: b) -> a:~~: cSource #
TestEquality ((:~~:) a :: k ->Type)Source #	Since: 4.10.0.0
Instance details Defined inData.Type.Equality Methods testEquality :: (a:~~: a0) -> (a:~~: b) ->Maybe (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 #
a~~ b =>Bounded (a:~~: b)Source #	Since: 4.10.0.0
Instance details Defined inData.Type.Equality Methods minBound :: a:~~: bSource # maxBound :: a:~~: bSource #
a~~ b =>Enum (a:~~: b)Source #	Since: 4.10.0.0
Instance details Defined inData.Type.Equality Methods succ :: (a:~~: b) -> a:~~: bSource # pred :: (a:~~: b) -> a:~~: bSource # toEnum ::Int -> a:~~: bSource # fromEnum :: (a:~~: b) ->Int Source # enumFrom :: (a:~~: b) -> [a:~~: b]Source # enumFromThen :: (a:~~: b) -> (a:~~: b) -> [a:~~: b]Source # enumFromTo :: (a:~~: b) -> (a:~~: b) -> [a:~~: b]Source # enumFromThenTo :: (a:~~: b) -> (a:~~: b) -> (a:~~: b) -> [a:~~: b]Source #
Eq (a:~~: b)Source #	Since: 4.10.0.0
Instance details Defined inData.Type.Equality Methods (==) :: (a:~~: b) -> (a:~~: b) ->Bool # (/=) :: (a:~~: b) -> (a:~~: b) ->Bool #
(Typeable i,Typeable j,Typeable a,Typeable b, a~~ b) =>Data (a:~~: b)Source #	Since: 4.10.0.0
Instance details Defined inData.Data Methods gfoldl :: (forall d b0.Data d => c (d -> b0) -> d -> c b0) -> (forall g. g -> c g) -> (a:~~: b) -> c (a:~~: b)Source # gunfold :: (forall b0 r.Data b0 => c (b0 -> r) -> c r) -> (forall r. r -> c r) ->Constr -> c (a:~~: b)Source # toConstr :: (a:~~: b) ->Constr Source # dataTypeOf :: (a:~~: b) ->DataType Source # dataCast1 ::Typeable t => (forall d.Data d => c (t d)) ->Maybe (c (a:~~: b))Source # dataCast2 ::Typeable t => (forall d e. (Data d,Data e) => c (t d e)) ->Maybe (c (a:~~: b))Source # gmapT :: (forall b0.Data b0 => b0 -> b0) -> (a:~~: b) -> a:~~: bSource # gmapQl :: (r -> r' -> r) -> r -> (forall d.Data d => d -> r') -> (a:~~: b) -> rSource # gmapQr :: (r' -> r -> r) -> r -> (forall d.Data d => d -> r') -> (a:~~: b) -> rSource # gmapQ :: (forall d.Data d => d -> u) -> (a:~~: b) -> [u]Source # gmapQi ::Int -> (forall d.Data d => d -> u) -> (a:~~: b) -> uSource # gmapM ::Monad m => (forall d.Data d => d -> m d) -> (a:~~: b) -> m (a:~~: b)Source # gmapMp ::MonadPlus m => (forall d.Data d => d -> m d) -> (a:~~: b) -> m (a:~~: b)Source # gmapMo ::MonadPlus m => (forall d.Data d => d -> m d) -> (a:~~: b) -> m (a:~~: b)Source #
Ord (a:~~: b)Source #	Since: 4.10.0.0
Instance details Defined inData.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#
a~~ b =>Read (a:~~: b)Source #	Since: 4.10.0.0
Instance details Defined inData.Type.Equality Methods readsPrec ::Int ->ReadS (a:~~: b)Source # readList ::ReadS [a:~~: b]Source # readPrec ::ReadPrec (a:~~: b)Source # readListPrec ::ReadPrec [a:~~: b]Source #
Show (a:~~: b)Source #	Since: 4.10.0.0
Instance details Defined inData.Type.Equality Methods showsPrec ::Int -> (a:~~: b) ->ShowS Source # show :: (a:~~: b) ->String Source # showList :: [a:~~: b] ->ShowS Source #

Type representations

Type-Indexed

dataTypeRep (a :: k)Source #

A concrete representation of a (monomorphic) type.TypeRep supports reasonably efficient equality.

Instances

TestEquality (TypeRep :: k ->Type)Source #
Instance details Defined inData.Typeable.Internal Methods testEquality ::TypeRep a ->TypeRep b ->Maybe (a:~: b)Source #
Eq (TypeRep a)Source #	Since: 2.1
Instance details Defined inData.Typeable.Internal Methods (==) ::TypeRep a ->TypeRep a ->Bool # (/=) ::TypeRep a ->TypeRep a ->Bool #
Ord (TypeRep a)Source #	Since: 4.4.0.0
Instance details Defined inData.Typeable.Internal Methods compare ::TypeRep a ->TypeRep a ->Ordering # (<) ::TypeRep a ->TypeRep a ->Bool # (<=) ::TypeRep a ->TypeRep a ->Bool # (>) ::TypeRep a ->TypeRep a ->Bool # (>=) ::TypeRep a ->TypeRep a ->Bool # max ::TypeRep a ->TypeRep a ->TypeRep a# min ::TypeRep a ->TypeRep a ->TypeRep a#
Show (TypeRep a)Source #
Instance details Defined inData.Typeable.Internal Methods showsPrec ::Int ->TypeRep a ->ShowS Source # show ::TypeRep a ->String Source # showList :: [TypeRep a] ->ShowS Source #

typeOf ::Typeable a => a ->TypeRep aSource #

patternApp ::forall k2 (t :: k2). () =>forall k1 (a :: k1 -> k2) (b :: k1). t ~ a b =>TypeRep a ->TypeRep b ->TypeRep tSource #

A type application.

For instance,

typeRep @(Maybe Int) === App (typeRep @Maybe) (typeRep @Int)

Note that this will also match a function type,

typeRep @(Int# -> Char)  ===App (App arrow (typeRep @Int#)) (typeRep @Char)

wherearrow :: TypeRep ((->) :: TYPE IntRep -> Type -> Type).

patternCon ::forall k (a :: k). () => IsApplication a ~ "" =>TyCon ->TypeRep aSource #

Pattern match on a type constructor

patternCon' ::forall k (a :: k). () => IsApplication a ~ "" =>TyCon -> [SomeTypeRep] ->TypeRep aSource #

Pattern match on a type constructor including its instantiated kind variables.

For instance,

App (Con' proxyTyCon ks) intRep = typeRep @(Proxy @Int)

will bring into scope,

proxyTyCon :: TyConks         == [someTypeRepType] :: [SomeTypeRep]intRep     == typeRepInt

patternFun ::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 funSource #

The function type constructor.

For instance,

typeRep @(Int -> Char) === Fun (typeRep @Int) (typeRep @Char)

typeRepTyCon ::TypeRep a ->TyCon Source #

Observe the type constructor of a type representation

rnfTypeRep ::TypeRep a -> ()Source #

Helper to fully evaluateTypeRep for use asNFData(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 kSource #

Observe the kind of a type.

splitApps ::TypeRep a -> (TyCon, [SomeTypeRep])Source #

Quantified

dataSomeTypeRepwhereSource #

A non-indexed type representation.

Constructors

SomeTypeRep ::forall k (a :: k). !(TypeRep a) ->SomeTypeRep

Instances

Eq SomeTypeRepSource #
Instance details Defined inData.Typeable.Internal Methods (==) ::SomeTypeRep ->SomeTypeRep ->Bool # (/=) ::SomeTypeRep ->SomeTypeRep ->Bool #
Ord SomeTypeRepSource #
Instance details Defined inData.Typeable.Internal Methods compare ::SomeTypeRep ->SomeTypeRep ->Ordering # (<) ::SomeTypeRep ->SomeTypeRep ->Bool # (<=) ::SomeTypeRep ->SomeTypeRep ->Bool # (>) ::SomeTypeRep ->SomeTypeRep ->Bool # (>=) ::SomeTypeRep ->SomeTypeRep ->Bool # max ::SomeTypeRep ->SomeTypeRep ->SomeTypeRep # min ::SomeTypeRep ->SomeTypeRep ->SomeTypeRep #
Show SomeTypeRepSource #	Since: 4.10.0.0
Instance details Defined inData.Typeable.Internal Methods showsPrec ::Int ->SomeTypeRep ->ShowS Source # show ::SomeTypeRep ->String Source # showList :: [SomeTypeRep] ->ShowS Source #

someTypeRep ::forall proxy a.Typeable a => proxy a ->SomeTypeRep Source #

Takes a value of typea 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 evaluateSomeTypeRep for use asNFData(rnf) implementation

Since: 4.10.0.0

Type constructors

dataTyCon #

Instances

Eq TyCon
Instance details Defined inGHC.Classes Methods (==) ::TyCon ->TyCon ->Bool # (/=) ::TyCon ->TyCon ->Bool #
Ord TyCon
Instance details Defined inGHC.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 #
Show TyConSource #	Since: 2.1
Instance details Defined inGHC.Show Methods showsPrec ::Int ->TyCon ->ShowS Source # show ::TyCon ->String Source # showList :: [TyCon] ->ShowS Source #

tyConPackage ::TyCon ->String Source #

tyConModule ::TyCon ->String Source #

tyConName ::TyCon ->String Source #

rnfTyCon ::TyCon -> ()Source #

Module names

dataModule #

Instances

Eq Module
Instance details Defined inGHC.Classes Methods (==) ::Module ->Module ->Bool # (/=) ::Module ->Module ->Bool #
Show ModuleSource #	Since: 4.9.0.0
Instance details Defined inGHC.Show Methods showsPrec ::Int ->Module ->ShowS Source # show ::Module ->String Source # showList :: [Module] ->ShowS Source #

moduleName ::Module ->String Source #

modulePackage ::Module ->String Source #

rnfModule ::Module -> ()Source #

Helper to fully evaluateTyCon for use asNFData(rnf) implementation

Since: 4.8.0.0

Movatterモバイル変換

The Typeable class

Propositional equality

Type representations

Type-Indexed

Quantified

Type constructors

Module names