#10931: layers-0.1 does not compile with ghc-7.10 (likely a regression from ghc-7.8) -------------------------------------+------------------------------------- Reporter: slyfox | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 7.10.2 checker) | Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: GHC rejects | Unknown/Multiple valid program | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): -------------------------------------+------------------------------------- Comment (by slyfox): Oh that's good! ghc-7.10 branch doesn't work though. I wonder when it was fixed. {{{ $ inplace/bin/ghc-stage2 --interactive T10931.hs GHCi, version 7.10.2.20151003: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling L ( T10931.hs, interpreted ) T10931.hs:28:17: Couldn't match type ‘m’ with ‘Inner (IdT m)’ ‘m’ is a rigid type variable bound by the instance declaration at T10931.hs:24:10 Expected type: Outer (IdT m) (Inner (IdT m)) Actual type: IdT m Relevant bindings include f :: forall (n :: * -> *). (n ~ Outer n (Inner n), Outer n ~ Outer (IdT m)) => Inner n a (bound at T10931.hs:28:9) bug :: (forall (n :: * -> *). (n ~ Outer n (Inner n), Outer n ~ Outer (IdT m)) => Inner n a) -> IdT m a (bound at T10931.hs:28:5) In the first argument of ‘IdC’, namely ‘f’ In the expression: IdC f In an equation for ‘bug’: bug f = IdC f Failed, modules loaded: none. }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10931#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler