#9897: Couldn't match type `Id (Id Char)' with `Char' -------------------------------------+------------------------------------- Reporter: erisco | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 7.8.3 checker) | Operating System: Windows Keywords: | Type of failure: GHC Architecture: x86_64 (amd64) | rejects valid program Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- 'foo' is expected to type check given that 'bar' and 'qux' type check. {{{ ghc_bug.hs:21:7: Couldn't match type `Id (Id Char)' with `Char' Expected type: (:.:) Id Id Char Actual type: Char In the expression: 'x' In an equation for `foo': foo = 'x' }}} {{{#!hs {-# LANGUAGE TypeOperators, TypeFamilies #-} module Main where type family (:.:) g f a where (:.:) g f a = g (f a) -- type family Id x where Id x = x -- -- Type checks bar :: Id (Id Char) bar = 'x' -- Type checks qux = 'x' :: (Id :.: Id) Char -- Couldn't match type `Id (Id Char)' with `Char' foo :: (Id :.: Id) Char foo = 'x' }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9897 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler