#12763: Incorrect behavior with empty functional dependencies -------------------------------------+------------------------------------- Reporter: diatchki | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 8.0.1 checker) | Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by Simon Peyton Jones <simonpj@…>): In [changeset:"801c26372742fc79bd3756bdcb710031c716c402/ghc" 801c2637/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="801c26372742fc79bd3756bdcb710031c716c402" Fundeps work even for unary type classes The functional-dependency improvement functions, improveFromAnother improveFromInstEnv had a side-condition that said the type class has to have at least two arguments. But not so, as Trac #12763 shows: class C a | -> a where ... is perfectly legal, albeit a bit of a corner case. }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12763#comment:1> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler