#10300: GHC rejects -------------------------------------+------------------------------------- Reporter: mhwombat | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: 10020 Differential Revisions: | -------------------------------------+------------------------------------- In GHC 7.8.4, the following code is legal: {{{ {-# LANGUAGE TypeFamilies, FlexibleContexts #-} class FiniteGrid g where type Size s size :: g -> Size g maxPossibleDistance :: g -> Int }}} But with GHC 7.10.1, it no longer compiles. The error message is: {{{ The associated type ‘Size’ mentions none of the type or kind variables of the class ‘FiniteGrid g’ In the class declaration for ‘FiniteGrid’ }}} I didn't see any mention of this in the migration guide, but perhaps there's another pragma I need to enable. I thought this might be related to https://ghc.haskell.org/trac/ghc/ticket/10020, but that bug is apparently fixed in GHC 7.10.1. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10300 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler