[GHC] #11707: Don't desugar large lists with build

[GHC]

#11707: Don't desugar large lists with build
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        Reporter:  bgamari           |                Owner:
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D2007
       Wiki Page:                    |
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Comment (by simonpj):

 See #11710; I think we should abandon the "static tail" idea described in
 `Note [Desugaring explicit lists]` entirely.

 Then, to avoid code bloat on very long lists, let's have the patch in this
 ticket, which ensures that if the list is long we revert to cons-list for.
 The goal here is just to eliminate mega-code-bloat in extreme cases.
 (Hence no real need for a flag to control `maxBuildLength`.

 I don't really like it; but I don't want BOTH hacks.  One is enough!

 Not worth burning much midnight oil on this one.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11707#comment:9>
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