Moduleproto-lens-0.7.1.5Haskell2010

Data.ProtoLens.Prism

This module defines the Prism type and combinators. Used for building Prisms for oneof fields.

type

type Prism s t a b = forall (p :: Type -> Type -> Type) (f :: Type -> Type). (Choice p, Applicative f) => p a (f b) -> p s (f t)

typetype Prism' s a = Prism s s a a

typetype AReview t b = Optic' Tagged Identity t b

value(#) :: AReview t b -> b -> t

Used for constructing Prism values.

_Just # 5 == Just 5

valueprism :: (b -> t) -> (s -> Either t a) -> Prism s t a b

Build a Control.Lens.Prism.Prism.

Either t a is used instead of Maybe a to permit the types of s and t to differ.

valueprism' :: (b -> s) -> (s -> Maybe a) -> Prism s s a b

This is usually used to build a Prism', when you have to use an operation like cast which already returns a Maybe.

value_Left

value_Right

value_Just :: (Choice p, Applicative f) => p a (f b) -> p (Maybe a) (f (Maybe b))

value_Nothing