[GHC] #9345: Data.List.inits is extremely slow

[GHC]

#9345: Data.List.inits is extremely slow
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              Reporter:  dfeuer      |            Owner:
                  Type:  bug         |           Status:  new
              Priority:  high        |        Milestone:  7.8.4
             Component:              |          Version:  7.8.3
  libraries/base                     |         Keywords:
            Resolution:              |     Architecture:  Unknown/Multiple
      Operating System:              |       Difficulty:  Easy (less than 1
  Unknown/Multiple                   |  hour)
       Type of failure:  Runtime     |       Blocked By:
  performance bug                    |  Related Tickets:
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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Comment (by nomeata):

 Didn’t look at the core yet, but this might be a case of non-linear
 recursion where an arity analysis in insufficient to get good code for a
 left fold, see 5.1.1 in
 http://pp.ipd.kit.edu/uploads/publikationen/breitner14callarity.pdf.

 I can have a closer look later. Can you, with these examples, please
 always include one complete self-contained file? Otherwise there is a risk
 that I might be testing with the wrong version of inits/scanl'/whatever. I
 assume you are on GHC HEAD?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9345#comment:22>
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