#12363: Type application for infix -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: feature request | Status: new Priority: lowest | Milestone: Component: Compiler | Version: 8.0.1 (Parser) | Keywords: Resolution: | TypeApplications 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): {{{#!hs a `asTypeIn` f = a where _ = f a }}} Checking the type of fails due to ambiguous `Functor`, `Applicative` constraints {{{#!hs flip id `asTypeIn` \x -> x <$> undefined <*> undefined <*> undefined }}} The user must either possess some prior knowledge and rewrite the expression {{{#!hs -- fixity of <$>, <*> flip id `asTypeIn` \x -> (<$>) @[] x undefined <*> undefined <*> undefined :: a -> (a -> b -> c) -> b -> c -- liftA3 f a b c = f <$> a <*> b <*> c flip id `asTypeIn` \x -> liftA3 @[] x undefined undefined undefined :: a -> (a -> b -> c) -> b -> c -- the return type of `_ <$> _ <*> _ <*> _` is some Applicative `f _` flip id `asTypeIn` \x -> (x <$> undefined <*> undefined <*> undefined :: [_]) :: a -> (a -> b -> c) -> b -> c }}} With infix type application they can directly write {{{#!hs flip id `asTypeIn` \x -> x <$> @[] undefined <*> undefined <*> undefined flip id `asTypeIn` \x -> x <$> @[] undefined <*> @[] undefined <*> @[] undefined }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12363#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler