#10224: Partial type signatures generate typed hole warnings -------------------------------------+------------------------------------- Reporter: quchen | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.10.2 Component: Compiler | Version: 7.10.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple warning at compile-time | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Changes (by goldfire): * status: closed => new * resolution: invalid => Comment: I find the warning message quite misleading. Here is my (uninteresting) case: {{{ foo :: _ -> Bool foo True = False foo False = True }}} I get this warning (with `-XPartialTypeSignatures`) {{{ Scratch.hs:18:8: warning: Found hole: _ :: Bool In the type signature for ‘foo’: _ -> Bool }}} I think of "hole" as something in an expression instead of a type. In a type, I thought it was called a "wildcard". In any case, `_ :: Bool` is wrong. My `_` certainly does not have type `Bool`. It has '''value''' `Bool`. Here is my suggested output: {{{ Scratch.hs:18:8: warning: Found type wildcard: `_' standing in for `Bool' In the type signature for ‘foo’: _ -> Bool }}} I'm reopening on the basis that, even if my hole vs. wildcard distinction is silly nitpicking, saying `_ :: Bool` is wrong and should be fixed. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10224#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler