Copyright	(C) 2017 Csongor Kiss
License	BSD3
Maintainer	Csongor Kiss <kiss.csongor.kiss@gmail.com>
Stability	experimental
Portability	non-portable
Safe Haskell	None
Language	Haskell2010

Data.Generics.Sum.Typed

Contents

Prisms

Description

Derive constructor-field-type-based prisms generically.

Synopsis

class AsType a s where

Prisms

class AsType a s where Source #

Sums that have a constructor with a field of the given type.

Minimal complete definition

injectTyped, projectTyped | _Typed

Methods

_Typed :: Prism' s a Source #

A prism that projects a constructor uniquely identifiable by the type of its field. Compatible with the lens package's Prism type.

>>> dog ^? _Typed @Dog
Just (MkDog {name = "Shep", age = Age 3})
>>> cat ^? _Typed @(Name, Age)
Just ("Mog",Age 5)
>>> dog ^? _Typed @Age
...
...
... The type Animal contains multiple constructors whose fields are of type Age.
... The choice of constructor is thus ambiguous, could be any of:
... Duck
... Turtle
...

injectTyped :: a -> s Source #

Inject by type.

projectTyped :: s -> Maybe a Source #

Project by type.

Instances

(Generic s, ErrorUnlessOne a s (CollectPartialType as (Rep s)), as ~ TupleToList a, ListTuple a as, GAsType (Rep s) as) => AsType a s Source #
Instance details Defined in Data.Generics.Sum.Typed Methods _Typed :: Prism' s a Source # injectTyped :: a -> s Source # projectTyped :: s -> Maybe a Source #