[GHC] #14436: Teach TemplateHaskell to generate less eye-hurting names

[GHC]

#14436: Teach TemplateHaskell to generate less eye-hurting names
-------------------------------------+-------------------------------------
           Reporter:  bgamari        |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:  8.4.1
          Component:  Compiler       |           Version:  8.2.1
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 If you look at the Haddocks for, e.g., the `singletons` package, one sees
 dozens of signatures containing unsightly names containing long integers.
 For instance, in the equation list for
 `Data.Singletons.Prelude.Either.IsLeft` we have
 {{{
   IsLeft (Left _z_6989586621679437436) = TrueSym0
   IsLeft (Right _z_6989586621679437439) = FalseSym0
 }}}

 For definitions with lots of variables things quickly become unreadable.

 These names appear this way because they are generated by
 TemplateHaskell's `newName` function. This name is ultimately converted to
 a GHC `System` name by `Convert.thRdrName`. Such `Name`s are then pretty-
 printed including their uniques (see `Name.pprSystem`). I'm not sure I see
 the rationale for this. Surely if the names are tidied properly (e.g.
 using `TyConRep.tidyType`) there should be no need for the unique suffix.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14436>
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