Bifunctor

Lean: Hale.Base.Bifunctor | Haskell: Data.Bifunctor

Overview

Typeclass for types with two covariant type parameters. Provides bimap, mapFst, mapSnd.

API Mapping

Instances

• Bifunctor Prod
• Bifunctor Sum
• Bifunctor Except
• LawfulBifunctor Prod
• LawfulBifunctor Sum
• LawfulBifunctor Except

Proofs & Guarantees

• bimap_id — bimap id id = id (via LawfulBifunctor)
• bimap_comp — bimap (f1 . f2) (g1 . g2) = bimap f1 g1 . bimap f2 g2 (via LawfulBifunctor)

Example

-- Map over both components of a pair
Bifunctor.bimap (· * 10) (· ++ "!") (1, "hello")
-- => (10, "hello!")