Data.Generics.Sum.Typed

Derive constructor-field-type-based prisms generically.

Prisms

class AsType a s where

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

Minimal complete definition

injectTyped, projectTyped | _Typed

Methods

_Typed :: Prism' s a

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

Inject by type.

projectTyped :: s -> Maybe a

Project by type.

Instances

AsType a Void

See Note [Uncluttering type signatures]

Defined in Data.Generics.Sum.Typed

Methods

_Typed :: Prism' Void a

injectTyped :: a -> Void

projectTyped :: Void -> Maybe a

(Generic s, ErrorUnlessOne a s (CollectPartialType as (Rep s)), as ~ TupleToList a, ListTuple a as, GAsType (Rep s) as, Defined (Rep s) (NoGeneric s ((Text "arising from a generic prism focusing on a constructor of type " :<>: QuoteType a) ': ([] :: [ErrorMessage]))) ()) => AsType a s

Defined in Data.Generics.Sum.Typed

Methods

_Typed :: Prism' s a

injectTyped :: a -> s

projectTyped :: s -> Maybe a

AsType Void a

See Note [Uncluttering type signatures]

Defined in Data.Generics.Sum.Typed

Methods

_Typed :: Prism' a Void

injectTyped :: Void -> a

projectTyped :: a -> Maybe Void