#13039: Add options to select GHCi prompt type errors -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: feature | Status: new request | Priority: low | Milestone: 8.4.1 Component: GHCi | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- [This SO post](http://stackoverflow.com/questions/41354231/how-can-i-set- up-haskells-ghci-to-interactively-evaluate-functions-to-their-sig) implicitly suggests some extra options for reporting type errors for expressions typed into GHCi. When GHCi reports a type error for an expression `e` typed at the prompt, it has effectively failed to check `void e :: IO ()` and `print e :: IO ()`. It always reports the error for the latter. There are three things a user may want, and I think options should control which ones are shown: 1. Why didn't `void e :: IO ()` check? 2. Why didn't `print e :: IO ()` check? 3. If any type could be inferred for `e`, what was it? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13039 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler