[GHC] #11051: GHCi with +t option set shows type representations

[GHC]

#11051: GHCi with +t option set shows type representations
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        Reporter:  bgamari           |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.11
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect result  |  Unknown/Multiple
  at runtime                         |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Description changed by bgamari:

Old description:

> hvr reported this morning that defining a data type in GHCi with the show
> types (`:set +t`) option set results in additional unexpected output. For
> instance,
>
> {{{
> $ inplace/bin/ghc-stage2 --interactive
> GHCi, version 7.11.20151101: http://www.haskell.org/ghc/  :? for help
> Prelude> :set +t
> Prelude> data Hi
> $tcHi :: TyCon
> $trModule :: Module
> data Hi
> Prelude>
> }}}
>
> The `$tcHi` and `$trModule` bindings are details of the Typeable
> implementation introduced in Phab:D1404 and should likely be hidden from
> the user.
>
> This would be trivial to fix except for the fact that we currently have
> no way to identify this sort of `Name`. In fact any knowledge that the
> name was generated appears to have been thrown away as early as
> `OccName.mkTyConRepSysOcc`.

New description:

 hvr reported this morning that defining a data type in GHCi with the show
 types (`:set +t`) option set results in additional unexpected output. For
 instance,

 {{{
 $ inplace/bin/ghc-stage2 --interactive
 GHCi, version 7.11.20151101: http://www.haskell.org/ghc/  :? for help
 Prelude> :set +t
 Prelude> data Hi
 $tcHi :: TyCon
 $trModule :: Module
 data Hi
 Prelude>
 }}}

 The `$tcHi` and `$trModule` bindings are details of the Typeable
 implementation introduced in Phab:D1404 and should likely be hidden from
 the user.

 This would be trivial to fix in `InteractiveUI.printTypeOfNames` except
 for the fact that we currently have no way to identify this sort of
 `Name`. In fact any knowledge that the name was generated appears to have
 been thrown away as early as `OccName.mkTyConRepSysOcc`.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11051#comment:1>
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