[GHC] #7730: :info and polykinds

[GHC]

#7730: :info and polykinds
--------------------------------------------+------------------------------
        Reporter:  monoidal                 |            Owner:  archblob
            Type:  bug                      |           Status:  patch
        Priority:  normal                   |        Milestone:  7.10.1
       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 Simon Peyton Jones <simonpj@…>):

 In [changeset:"b4856f9f4f0fb3db473901b247d3fa94a11c25a0/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="b4856f9f4f0fb3db473901b247d3fa94a11c25a0"
 Do pretty-printing of TyThings via IfaceDecl (Trac #7730)

 All the initial work on this was done fy 'archblob' (fcsernik at gmail.com);
 thank you!

 I reviewed the patch, started some tidying, up and then ended up in a huge
 swamp of changes, not all of which I can remember now.  But:

 * To suppress kind arguments when we have -fno-print-explicit-kinds,
     - IfaceTyConApp argument types are in a tagged list IfaceTcArgs

 * To allow overloaded types to be printed with =>, add IfaceDFunTy to
 IfaceType.

 * When printing data/type family instances for the user, I've made them
   print out an informative RHS, which is a new feature. Thus
         ghci> info T
         data family T a
         data instance T Int = T1 Int Int
         data instance T Bool = T2

 * In implementation terms, pprIfaceDecl has just one "context" argument,
   of type IfaceSyn.ShowSub, which says
        - How to print the binders of the decl
          see note [Printing IfaceDecl binders] in IfaceSyn
        - Which sub-comoponents (eg constructors) to print

 * Moved FastStringEnv from RnEnv to OccName

 It all took a ridiculously long time to do.  But it's done!
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7730#comment:51>
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