#11350: Allow visible type application in patterns -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.1 Resolution: | Keywords: | TypeApplications PatternSynonyms Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #11385 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by Iceland_jack): Have only referenced this in passing: Allow type application for methods {{{#!hs class Semigroup a where (<>) @a :: a -> a -> a class Semigroup a => Monoid a where mempty @a :: a }}} and their instances with some #12363 {{{#!hs instance (Semigroup a, Semigroup b) => Semigroup (a, b) where (<>) @(a, b) :: (a, b) -> (a, b) -> (a, b) (a1, b1) <> @(a, b) (a2, b2) = (a1 <> @a a2, b1 <> @b b2) instance (Monoid a, Monoid b) => Monoid (a, b) where mempty @(a, b) :: (a, b) mempty @(a, b) = (mempty @a, mempty @b) instance Semigroup b => Semigroup (a -> b) where (<>) @(a -> b) :: (a -> b) -> (a -> b) -> (a -> b) (f <> @(a -> b) g) x = f x <> @b g x -- ^ not recommended style class Monoid b => Monoid (a -> b) where mempty @(a -> b) :: a -> b mempty @(a -> b) _ = mempty @b }}} The type variables should probably match the order of application a regular expression context. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11350#comment:12 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler