#13026: RFC functions for sums and products -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: libraries/base | Version: 8.0.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Description changed by Iceland_jack: @@ -6,1 +6,1 @@ - {{{!hs + {{{#!hs New description: I'll ask on the libraries mailing list depending on feedback. Adding these to `Data.Functor.Sum`, `Data.Functor.Product` a la `Control.Arrow` {{{#!hs (||||) :: (f a -> b) -> (g a -> b) -> ((Sum f g) a -> b) f |||| g = \case InL fa -> f fa InR ga -> g ga (&&&&) :: (a -> f b) -> (a -> g b) -> (a -> (Product f g) b) (f &&&& g) a = f a `Pair` g a }}} `||||` is used in "Monad transformers and modular algebraic effects: What binds them together" in section 2.4, the names are up for discussion -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13026#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler