#9902: Type family, pattern not matching -------------------------------------+------------------------------------- Reporter: erisco | Owner: Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 (Type checker) | Keywords: Resolution: invalid | Architecture: x86_64 (amd64) Operating System: MacOS X | Difficulty: Unknown Type of failure: GHC | Blocked By: rejects valid program | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by erisco): Thanks Simon I see the issue now. Sorry to be using the bug tracker as a Q&A rather than reporting real bugs. There seems to be a limited number of people with knowledge of type level programming on #haskell which is where I go for help. Also, it has been too easy to mistakenly apply familiarities seen at the value level and has resulted in much of the confusion. I was under the impression that the correct kinds for `:.:` would be inferred because a solution exists, rather than giving an error, but that does not appear to be the case then. Will inference generally happen from innermost to outermost without backtracking? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9902#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler