[GHC] #9557: Deriving instances is slow

[GHC]

#9557: Deriving instances is slow
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              Reporter:  Feuerbach   |            Owner:
                  Type:  bug         |           Status:  closed
              Priority:  normal      |        Milestone:
             Component:  Compiler    |          Version:  7.8.3
            Resolution:  duplicate   |         Keywords:
      Operating System:              |     Architecture:  Unknown/Multiple
  Unknown/Multiple                   |       Difficulty:  Unknown
       Type of failure:              |       Blocked By:
  None/Unknown                       |  Related Tickets:  #8731
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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Comment (by Feuerbach):

 carter: why do you think they are the same?

 There, the reason is the large number of field selectors.

 Here, I was able to check that removing some of the class derivations
 reduces the compile time significantly.

 I'm not convinced that fixing that issue will necessarily fix this one;
 they may (or may not) be inefficiencies in different parts of code.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9557#comment:4>
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