#11642: Heterogeneous type equality evidence ignored -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: bug | Status: new Priority: high | Milestone: 8.0.1 Component: Compiler (Type | Version: 7.10.3 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): Wiki Page: | -------------------------------------+------------------------------------- Comment (by bgamari): Judging by the `-ddump-tc-trace` output (for the fully expanded `case` version given in comment:2), the problem is that this wanted is unsolved, {{{ (~#) k_a1Lg[ssk] k_a1Lg[ssk] x_a1Li[ssk] ((TYPE |> <Levity>_N -> Sym cobox_a1Mi) 'Lifted) (CNonCanonical)} }}} given these givens, {{{ (~#) * * k_a1L4[ssk] (f_a1Ld[ssk] x_a1Le[ssk]) (~#) (k_a1Lc[ssk] -> *) (k_a1Lc[ssk] -> *) f_a1Ld[ssk] (f_a1Lh[ssk] x_a1Li[ssk]) (~#) * * (* -> * -> *) (k_a1Lg[ssk] -> k_a1Lc[ssk] -> *) (~#) (* -> * -> *) (k_a1Lg[ssk] -> k_a1Lc[ssk] -> *) (->) f_a1Lh[ssk] (~#) * * k_a1Lg[ssk] k_a1L6[ssk] (~#) k_a1Lg[ssk] k_a1L6[ssk] x_a1Li[ssk] a_a1L7[ssk] }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11642#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler