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

[GHC]

#9394: Show data/type family instances with ghci's :info command
-------------------------------------+-------------------------------------
       Reporter:  s9gf4ult           |                   Owner:
           Type:  feature request    |                  Status:  new
       Priority:  normal             |               Milestone:
      Component:  GHCi               |                 Version:  7.6.3
       Keywords:  ghci               |        Operating System:
   Architecture:  Unknown/Multiple   |  Unknown/Multiple
     Difficulty:  Unknown            |         Type of failure:
     Blocked By:                     |  None/Unknown
Related Tickets:                     |               Test Case:
                                     |                Blocking:
                                     |  Differential Revisions:
-------------------------------------+-------------------------------------
 Current version of ghci (7.6.3) does not show data instances. For example,
 I have some Yesod application and I want to see all data constructors of
 (Route App) data family instance:

 {{{#!hs
 *Application> :info Route App
 class Eq
         (Route
            a) => yesod-routes-1.2.0.6:Yesod.Routes.Class.RenderRoute a
 where
   data family Route a1
   ...
         -- Defined in `yesod-routes-1.2.0.6:Yesod.Routes.Class'
 instance Eq (Route App) -- Defined at Foundation.hs:48:1
 instance Read (Route App) -- Defined at Foundation.hs:48:1
 .................
 }}}

 It just shows info about `Route`, then info about `App` separately. When I
 try this:

 {{{#!hs
 *Application> :info (Route App)

 <interactive>:1:2: parse error on input `Route'
 }}}

 I am getting parse error.

 I offer to use this syntax (with parentheses) to show info about instance
 of data/type family, namely, data constructors and such stuff, just like
 for ordinal `data`.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9394>
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