[GHC] #7730: :info and polykinds

[GHC]

#7730: :info and polykinds
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        Reporter:  monoidal                 |            Owner:  archblob
            Type:  bug                      |           Status:  new
        Priority:  normal                   |        Milestone:  7.8.3
       Component:  Compiler (Type checker)  |          Version:  7.6.2
      Resolution:                           |         Keywords:
Operating System:  Unknown/Multiple         |     Architecture:
 Type of failure:  None/Unknown             |  Unknown/Multiple
       Test Case:                           |       Difficulty:  Unknown
        Blocking:                           |       Blocked By:
                                            |  Related Tickets:  #8776
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Comment (by archblob):

 Regarding (2), currently ifAxiom just gets the name of the axiom, so as
 you say we could also get the name from the ``` TyCon ``` and other info
 we need, that's what I was working on now but it just doesn't feel right
 to add all that redundant information in there.```pprTyThing``` gets
 called on a family instance tycon because when we request info about a
 data constructor of a family instance we call ```tyThingParent_maybe```
 that will return the immediate parent and in this case it is the family
 instance tycon. We could bypass this and instead return a ``` FamInst ```
 in the appropriate case, like this we don't need to add any extra info to
 ``` IfaceData ```. ```tyThingParent_maybe``` is only used for pretty
 printing so if you think this is a good idea it will not complicate things
 ?

 Regarding the context printing properly I thought that needs no mentioning
 because you suggested how it should be fixed in another comment here and
 in #8876, I just wanted to get these other things right first.

 Andrei

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7730#comment:22>
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