#12919: Equality not used for substitution -------------------------------------+------------------------------------- Reporter: int-index | Owner: goldfire Type: bug | Status: new Priority: highest | Milestone: Component: Compiler (Type | Version: 8.0.1 checker) | Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: Type of failure: GHC rejects | Unknown/Multiple valid program | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by goldfire): While I don't see what's going wrong here -- and something surely is -- I'm not as concerned about `flatten_co`. The second return value from the function is always ignored and should indeed be removed. It is a coercion relating the output coercion to the input, as constructed by `mkProofIrrelCo`. (Yes, this is a coercion relating two coercions.) These coercions are cheap to make, as any two coercions proving the same proposition are considered equal. Is this holding you up today? Or is it OK to wait a few weeks? I see the "highest" priority and will surely fix for 8.2. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12919#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler