#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: | -------------------------------------+------------------------------------- Comment (by Iceland_jack): Some other {{{#!hs type f ~> g = forall x. f x -> g x (****) :: f ~> f' -> g ~> g' -> Product f g ~> Product f' g' (f **** g) (fa `Pair` ga) = f fa `Pair` g ga first' :: f ~> f' -> Product f g ~> Product f' g first' = (**** id) second' :: g ~> g' -> Product f g ~> Product f g' second' = (id ****) (++++) :: f ~> f' -> g ~> g' -> Sum f g ~> Sum f' g' f ++++ g = \case InL fa -> InL (f fa) InR ga -> InR (g ga) left' :: f ~> f' -> Sum f g ~> Sum f' g left' = (++++ id) right' :: g ~> g' -> Sum f g ~> Sum f g' right' = (id ++++) }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13026#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler