[GHC] #9923: Offer copy-on-GC sliced arrays

[GHC]

#9923: Offer copy-on-GC sliced arrays
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        Reporter:  dfeuer            |                   Owner:  simonmar
            Type:  feature request   |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Runtime System    |                 Version:  7.11
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  None/Unknown      |  Unknown/Multiple
      Blocked By:                    |               Test Case:
 Related Tickets:                    |                Blocking:
                                     |  Differential Revisions:
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Comment (by dfeuer):

 Replying to [comment:1 svenpanne]:
 > Hmmm, I doubt that this would work: The proposal means that the garbage
 collector must allocate memory during collections, which is quite the
 opposite what it is supposed to do. Put another way: If somebody (SimonM?)
 thinks that this is possible, I would be very interested in the details.
 Even if this somehow works, there are several pathological cases like
 having lots of 999999-element slices of a 1000000-element array.
 >
 > Short-circuiting projection functions is OK (IIRC nhc did that first)
 because one doesn't have to allocate, but slicing is not really
 projecting.

 Yes, it would have to allocate while collecting, but I think this happens
 anyway. As for pathological cases, "Doctor! It hurts when I do ''this''!
 Don't do that." The suggested mechanism would not replace the usual sort
 of array slicing in general; it would be an alternative mechanism for
 situations where it was useful.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9923#comment:2>
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