#14694: Can't coerce given assumptions -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Resolution: | Keywords: Roles 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 simonpj): Just to be clear about what Richard means when he says "incompleteness", it's this: there is a solution, we don't find it. Specifically we have {{{ [G] (cat a b) ~R (a -> f b) [W] cat a b ~R (a -> WF f b) }}} Applying the `[G]` transitively with the `[W]` wanted, we'd get {{{ [W] (a -> f b) ~R (a -> WF f b) }}} which we can certainly solve easily. It's annoying that GHC's solver can't spot this. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14694#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler