#9173: Better type error messages -------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by thomie): Reddit user physicologist [https://www.reddit.com/r/haskell/comments/3m2iiv/ghc_error_messages/cvckb3c writes]: While I love the the proposal in the ticket, I feel that a purely textual change to the error message could be a great boon without changing a single line of code. "Expected" versus "actual" don't really the nature of the problem. For example, what is the type of foo in the following {{{ foo :: Int foo = "Howdy!" }}} Is foo actually an Int, since that was declared? Did the compiler expect foo to be a String, since that's what we passed it? Or is foo actually a "String", since that's what it contained, but the compiler expected a Int, since that's what we told it would be contained? Perhaps just changing {{{ Couldn't match expected type 'Foo' with actual type 'Bar' }}} to {{{ Couldn't match declared type 'Foo' against a value of type `Bar' }}} might make things clearer? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9173#comment:8 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler