has-0.2.1: Pliant data types and functions Source code Contents Index

Data.Has

Description

Provides some pliant data types and functions.

Synopsis

data a :*: b = a :*: b class Has e s where inj :: e -> s -> s prj :: s -> e upd :: Has e s => (e -> e) -> s -> s

Documentation

data a :*: b Source

Represents Type level list. Constructors a :*: b Instances (MayHave e h, MayHave e t) => MayHave e (:*: h t) (TyOr x y b, Contains e h x, Contains e t y) => Contains e (:*: h t) b (Bounded a, Bounded b) => Bounded (:*: a b) (Eq a, Eq b) => Eq (:*: a b) (Ord a, Ord b) => Ord (:*: a b) (Read a, Read b) => Read (:*: a b) (Show a, Show b) => Show (:*: a b) (Arbitrary a, Arbitrary b) => Arbitrary (:*: a b) (CoArbitrary a, CoArbitrary b) => CoArbitrary (:*: a b) (Monoid a, Monoid b) => Monoid (:*: a b)

class Has e s where Source

Provides plient function. Holds e == prj (inj e s) for all s and e. Methods inj :: e -> s -> s Source Injects a value of type e into s if s contains the type e. prj :: s -> e Source Projects a value of type e out from s if s contains the type e. Instances (MayHave e s, Contains e s TyTrue) => Has e s

upd :: Has e s => (e -> e) -> s -> s Source

Updates a value e in s, using given function e -> e.

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