[GHC] #9427: Do finer-grained dependency analysis to infer more general kinds on type/class declarations

[GHC]

#9427: Do finer-grained dependency analysis to infer more general kinds on
type/class declarations
-------------------------------------+-------------------------------------
       Reporter:  goldfire           |                   Owner:
           Type:  bug                |                  Status:  new
       Priority:  normal             |               Milestone:
      Component:  Compiler           |                 Version:  7.8.2
       Keywords:                     |        Operating System:
   Architecture:  Unknown/Multiple   |  Unknown/Multiple
     Difficulty:  Unknown            |         Type of failure:
     Blocked By:                     |  None/Unknown
Related Tickets:                     |               Test Case:
                                     |                Blocking:
                                     |  Differential Revisions:
-------------------------------------+-------------------------------------
 In the resolution to #9200, as detailed
 [wiki:GhcKinds/KindInference#Apossiblevariation here], we identified an
 area for improvement. This improvement was not implemented in the fix for
 #9200. This ticket will track just this improvement.

 (In brief: we can do better dependency analysis on mutually recursive
 type/class declarations to allow more kinds to generalize earlier. This
 would lessen the burden on programmers to put in kind annotations. See the
 wiki page.)

 A solid but unfinished attempt is [https://github.com/goldfirere/ghc/tree
 /re-sort-non-cusk-decls here].

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9427>
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