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

_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 = 3})
>>> dog ^? _Typed @Age
Nothing
>>> cat ^? _Typed @(Name, Age)
Just ("Mog",5)
>>> duck ^? _Typed @Age
Just 2

Instances

(Generic s, ErrorUnlessOne a s (CountPartialType a (Rep s)), GAsType (Rep s) a) => AsType a s

Methods

_Typed :: Prism' s a