[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           |           Version:  8.2.1
  Libraries                          |
           Keywords:  Typeable       |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):  Phab:D4084     |         Wiki Page:
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 There are two problems.

 1. Showing typereps of tuples can produce unnecessary parentheses:

 {{{
 Prelude K T> typeRep @(Int, Maybe Bool)
 (Int,(Maybe Bool))
 }}}

    The fix is trivial.

 2. Showing typereps of ticked (i.e., lifted) tuples and lists gives hard-
 to-read results, because it does not use the usual special syntax:

 {{{
 Prelude K T> typeRep @'(Int, Maybe Bool)
 '(,) * * Int (Maybe Bool)

 Prelude K T> typeRep @'[1,2,3]
 ': Nat 1 (': Nat 2 (': Nat 3 ('[] Nat)))
 }}}

    Fixing the lifted tuple case is trivial. Fixing the lifted list case is
 slightly less trivial, but not hard.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14341>
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