[GHC] #9805: Use TrieMaps to speed up type class instance lookup

[GHC]

#9805: Use TrieMaps to speed up type class instance lookup
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        Reporter:  ezyang            |                   Owner:  ezyang
            Type:  task              |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler (Type    |                 Version:  7.9
  checker)                           |                Keywords:
      Resolution:                    |            Architecture:
Operating System:  Unknown/Multiple  |  Unknown/Multiple
 Type of failure:  None/Unknown      |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
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Comment (by simonpj):

 Yes, and that is indeed a pain.

 Perhaps we should ''always'' do unification, which generalises matching,
 and distinguish the match cases post-hoc.

 Re the key thing, I think we may just want to keep (key,value) pairs at
 the leaves, rather than just values.  Better than reconstructing the key
 from the tree.

 Simon

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9805#comment:11>
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