#9182: Empty case analysis for function clauses ------------------------------------+------------------------------------- Reporter: dfranke | Owner: Type: feature request | Status: new Priority: low | Milestone: Component: Compiler | Version: 7.8.2 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Thanks to `-XEmptyCase`, the following is legal: {{{ module Empty where data Empty empty :: Empty -> a empty x = case x of { } }}} However, if I leave off the last line, GHC will complain that `The type signature for ‘empty’ lacks an accompanying binding`. I think this program should be accepted. It isn't that I'm not giving a definition for `empty`; it's that I'm defining it to be a function with no accompanying equations, as could be represented in Template Haskell by $(return [FunD (mkName "empty") []]) Currently, this too is rejected, with GHC complaining `Function binding for ‘empty’ has no equations`. I think this should be legal, with an empty list of clauses in a function definition being treated the same way as an empty list of matches in a case expression. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9182 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler