Data.GADT.Show

Showing

class GShow t where

Show-like class for 1-type-parameter GADTs. GShow t => ... is equivalent to something like (forall a. Show (t a)) => .... The easiest way to create instances would probably be to write (or derive) an instance Show (T a), and then simply say:

instance GShow t where gshowsPrec = showsPrec

Methods

gshowsPrec :: Int -> t a -> ShowS

Instances

GShow (TypeRep :: k -> Type)

Defined in Data.GADT.Internal

Methods

gshowsPrec :: Int -> TypeRep a -> ShowS

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

Defined in Data.GADT.Internal

Methods

gshowsPrec :: Int -> (a :~: a0) -> ShowS

GShow (GOrdering a :: k -> Type)

Defined in Data.GADT.Internal

Methods

gshowsPrec :: Int -> GOrdering a a0 -> ShowS

(GShow a, GShow b) => GShow (Product a b :: k -> Type)

>>> gshow (Pair Refl Refl :: Product ((:~:) Int) ((:~:) Int) Int)
"Pair Refl Refl"

Defined in Data.GADT.Internal

Methods

gshowsPrec :: Int -> Product a b a0 -> ShowS

(GShow a, GShow b) => GShow (Sum a b :: k -> Type)

>>> gshow (InL Refl :: Sum ((:~:) Int) ((:~:) Bool) Int)
"InL Refl"

Defined in Data.GADT.Internal

Methods

gshowsPrec :: Int -> Sum a b a0 -> ShowS

gshows :: GShow t => t a -> ShowS

gshow :: GShow t => t a -> String

Reading

class GRead t where

Read-like class for 1-type-parameter GADTs. Unlike GShow, this one cannot be mechanically derived from a Read instance because greadsPrec must choose the phantom type based on the String being parsed.

Methods

greadsPrec :: Int -> GReadS t

Instances

GRead (GOrdering a :: k -> Type)

Defined in Data.GADT.Internal

Methods

greadsPrec :: Int -> GReadS (GOrdering a)

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

Defined in Data.GADT.Internal

Methods

greadsPrec :: Int -> GReadS ((:~:) a)

(GRead a, GRead b) => GRead (Sum a b :: k -> Type)

Defined in Data.GADT.Internal

Methods

greadsPrec :: Int -> GReadS (Sum a b)

type GReadS t = String -> [(Some t, String)]

GReadS t is equivalent to ReadS (forall b. (forall a. t a -> b) -> b), which is in turn equivalent to ReadS (Exists t) (with data Exists t where Exists :: t a -> Exists t)

greads :: GRead t => GReadS t

gread :: GRead t => String -> (forall a. t a -> b) -> b

greadMaybe :: GRead t => String -> (forall a. t a -> b) -> Maybe b

>>> greadMaybe "InL Refl" mkSome :: Maybe (Some (Sum ((:~:) Int) ((:~:) Bool)))
Just (mkSome (InL Refl))

>>> greadMaybe "garbage" mkSome :: Maybe (Some ((:~:) Int))
Nothing

getGReadResult :: Some tag -> (forall a. tag a -> b) -> b

mkGReadResult :: tag a -> Some tag