Safe Haskell | Safe-Inferred |
---|---|
Language | Haskell2010 |
Synopsis
- class (forall i. Contravariant left target (Flip v i), forall i. Covariant right target (v i)) => Divariant left right target v where
- (>->) :: left a b -> right c d -> target (v b c) (v a d)
Documentation
class (forall i. Contravariant left target (Flip v i), forall i. Covariant right target (v i)) => Divariant left right target v where Source #
When providing a new instance, you should ensure it satisfies: * Identity: identity >-> identity ≡ identity * Interpreted: f . g >-> h . i ≡ g >-> h . f >-> i