#9636: Function with type error accepted -------------------------------------+------------------------------------- Reporter: augustss | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 Resolution: | Keywords: Operating System: | Architecture: Unknown/Multiple Unknown/Multiple | Difficulty: Unknown Type of failure: | Blocked By: None/Unknown | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by goldfire): Simon and I chatted about this this morning and we thought that your program is a little suspect, perhaps, but not type-incorrect. After all, `T Bool` is inhabited, by `undefined`. To me, suggesting that `T Bool` is unequivocally an error is somewhat like saying `Void` is an error. On the other hand, writing `T Bool` is probably a mistake. We thought a good solution here would be to report a warning in this case. Specifically, warn whenever a closed type family is called on arguments that are apart from all the family's left-hand sides. Would that be a good solution? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9636#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler