Re: #16406: Array code works with GHC 8.4.4, hangs with GHC 8.6.4

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#16406: Array code works with GHC 8.4.4, hangs with GHC 8.6.4
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        Reporter:  arybczak          |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  libraries         |              Version:  8.6.4
  (other)                            |
      Resolution:                    |             Keywords:  array
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by bgamari):

 The report has this to say about accumArray:

 > If the accumulating function is strict, then accumArray is strict in the
 values, as well as the indices, in the association list. Thus, unlike
 ordinary arrays built with array, accumulated arrays should not in general
 be recursive.

 It does sound like we are within our rights to be strict here. However,
 perhaps we should document this strictness a bit better

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16406#comment:10>