[GHC] #9394: Show data/type family instances with ghci's :info command

[GHC]

#9394: Show data/type family instances with ghci's :info command
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        Reporter:  s9gf4ult          |                   Owner:
            Type:  feature request   |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  GHCi              |                 Version:  7.6.3
      Resolution:                    |                Keywords:  ghci
Operating System:  Unknown/Multiple  |  newcomer
 Type of failure:  None/Unknown      |            Architecture:
      Blocked By:                    |  Unknown/Multiple
 Related Tickets:                    |               Test Case:
                                     |                Blocking:
                                     |  Differential Revisions:
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Comment (by javran):

 Newcomer here. I'm interested in this issue. Not sure about the
 difficulty, so I'll just give some of my thoughts and see if it works out.

 Currently `:info` isn't doing a good job parsing its arguments, it simply
 uses `words` to separate arguments so that for `:info (Route App)`, what
 will `:info` really see is two separated arguments: `(Route` and `App)`.

 I think the first step is to have some better handling on `:info`, maybe
 allowing it to accept a list of either names (as before) or type
 applications (use parentheses to disambiguate it from names).

 And then we can probably leverage some type checking facilities to help
 filtering out instances.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9394#comment:6>
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