[GHC] #11660: Remove Type pretty-printer in favor of IfaceType

[GHC]

#11660: Remove Type pretty-printer in favor of IfaceType
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        Reporter:  bgamari           |                Owner:
            Type:  task              |               Status:  patch
        Priority:  high              |            Milestone:  8.2.1
       Component:  Compiler          |              Version:  7.10.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #12550, #12447,   |  Differential Rev(s):  Phab:D2528
  #11786, #11549, #12024, #12697,    |
  #12510                             |
       Wiki Page:                    |
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Comment (by bgamari):

 The other issue is that rendering tuples, sums, and other built-in syntax
 things becomes a bit tricker. While previously we had access to the
 `TyCon` and could therefore simply use `isTupleTyCon_maybe` to identify
 tuples, now we only have the `IfaceTyCon` which can't easily be identified
 since it only gives us a `Name`.

 I can imagine a few (all fairly non-satisfactory) options here:

  * build a finite map of `TyCon` `Name`s that require special treatment.
 This is quite bad as it brings us back to the situation of building a map
 of a technically-infinite family of tycons
  * capture some analogue of `AlgTyConRhs` (which allows us to distinguish
 tuple `TyCon`s) in `IfaceTyCon`

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11660#comment:13>
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