#9725: Constraint deduction failure -------------------------------------+------------------------------------- Reporter: heisenbug | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 (Type checker) | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Unknown Unknown/Multiple | Blocked By: Type of failure: GHC | Related Tickets: rejects valid program | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by simonpj): Ah I see. You are right. But this is pretty coincidental. If the wanted was `[W] ent ~ M` we'd be out of luck. And taking account of the coincidence is far from straightforward; it would be a significant complication in the solver, which will be redundant when your stuff lands. So I propose to wait. Sorry Gabor, but Richard's stuff is itself a major increment, and I just don't know what a simple cut-down version might look like. ETA is up to Richard. Meanwhile, `usafeCoerce` may be needed. Simon -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9725#comment:11 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler