[GHC] #15827: Explicit foralls in type family equations are pretty-printed inconsistently (and strangely, at times)

[GHC]

#15827: Explicit foralls in type family equations are pretty-printed inconsistently
(and strangely, at times)
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        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.7
      Resolution:                    |             Keywords:  TypeFamilies
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by RyanGlScott):

 OK. In that case, my tentative plan is to:

 * Not print the coercion variables at all.
 * Pretty-print the type variables by first converting them to
 `IfaceForAllBinder`s (defaulting their visibilities to specified //à la//
 `mkSpecForAllTys`) and then using a function like `pprIfaceForAll` to
 pretty-print them with the explicit `forall` syntax.

 Does that sound reasonable?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15827#comment:3>
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