#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: -------------------------------------+------------------------------------- Comment (by mpickering): I think this is the expected behaviour. From the user guide:

By default, the type-checker will report an error message for each hole in a partial type signature, informing the programmer of the inferred type. When the -XPartialTypeSignatures flag is enabled, the type-checker will accept the inferred type for each hole, generating warnings instead of errors. Additionally, these warnings can be silenced with the -fno- warn-partial-type-signatures flag.

-- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10224#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#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

#10224: Partial type signatures generate typed hole warnings -------------------------------------+------------------------------------- Reporter: quchen | Owner: Type: bug | Status: closed Priority: normal | Milestone: 7.10.2 Component: Compiler | Version: 7.10.1 Resolution: fixed | 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 simonpj): * status: new => closed * resolution: => fixed Comment: Good idea -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10224#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10224: Partial type signatures generate typed hole warnings -------------------------------------+------------------------------------- Reporter: quchen | Owner: Type: bug | Status: closed Priority: normal | Milestone: 7.10.2 Component: Compiler | Version: 7.10.1 Resolution: fixed | 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: -------------------------------------+------------------------------------- Comment (by Thomas Miedema ): In [changeset:"f607393b7ffa8a06417e3f1263d2610d6bfe8279/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="f607393b7ffa8a06417e3f1263d2610d6bfe8279" Testsuite: accept new stderr for T9497{a,b,c}-run (#10224) }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10224#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler