[GHC] #10985: When a "non-exhaustive pattern"-error occurs, output the arguments (if possible)

[GHC]

#10985: When a "non-exhaustive pattern"-error occurs, output the arguments (if
possible)
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           Reporter:  Watercrystal   |             Owner:
               Type:  feature        |            Status:  new
  request                            |
           Priority:  lowest         |         Milestone:
          Component:  Compiler       |           Version:  7.10.2
  (Debugging)                        |
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:  #10972
Differential Rev(s):                 |         Wiki Page:
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 For Haskell-beginners like me, "non-exhaustive pattern"-errors occur
 rather often and they can take some time to fix. While it is obvious that
 one has made a critical mistake when writing a function, I don't think
 adding some debugging help would certainly not be bad. I know that this
 feature only really makes sense when working with types that are instances
 of `Show`, but then again beginners find themselves working with these
 types.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10985>
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