proto-lens-0.7.0.0: A lens-based implementation of protocol buffers in Haskell.

Safe HaskellSafe
LanguageHaskell2010

Data.ProtoLens.Prism

Description

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

Synopsis

Documentation

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

type Prism' s a = Prism s s a a Source #

type AReview t b = Optic' Tagged Identity t b Source #

(#) :: AReview t b -> b -> t infixr 8 Source #

Used for constructing Prism values.

_Just # 5 == Just 5

prism :: (b -> t) -> (s -> Either t a) -> Prism s t a b Source #

Build a Prism.

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

prism' :: (b -> s) -> (s -> Maybe a) -> Prism s s a b Source #

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

_Left :: Prism (Either a c) (Either b c) a b Source #

_Right :: Prism (Either c a) (Either c b) a b Source #

_Just :: Prism (Maybe a) (Maybe b) a b Source #