[GHC] #13039: Add options to select GHCi prompt type errors

[GHC]

#13039: Add options to select GHCi prompt type errors
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        Reporter:  dfeuer            |                Owner:
            Type:  feature request   |               Status:  new
        Priority:  low               |            Milestone:  8.4.1
       Component:  GHCi              |              Version:  8.0.1
      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:                    |
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Description changed by dfeuer:

@@ -1,2 +1,2 @@
- [This SO post](http://stackoverflow.com/questions/41354231/how-can-i-set-
- up-haskells-ghci-to-interactively-evaluate-functions-to-their-sig)
+ [http://stackoverflow.com/questions/41354231/how-can-i-set-up-haskells-
+ ghci-to-interactively-evaluate-functions-to-their-sig This SO post]

New description:

 [http://stackoverflow.com/questions/41354231/how-can-i-set-up-haskells-
 ghci-to-interactively-evaluate-functions-to-their-sig This SO post]
 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?

--

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13039#comment:2>
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