[GHC] #14341: Show instance for TypeReps is a bit broken

[GHC]

#14341: Show instance for TypeReps is a bit broken
-------------------------------------+-------------------------------------
        Reporter:  dfeuer            |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Core Libraries    |              Version:  8.2.1
      Resolution:                    |             Keywords:  Typeable
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D4084
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by PhilippD):

 There's also a problem with displaying partially applied tuple type
 constructors:

 {{{
 λ> typeRep @((,,))
 ()
 λ> typeRep @((,,,,,,,) Int Word)
 (Int,Word)
 }}}

 The problem seems to be that `showTypeable` doesn't check the arity of the
 constructor and just applies `showArgs` to the type arguments.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14341#comment:3>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler