[GHC] #12665: Make Read instances faster, and make them fail fast

[GHC]

#12665: Make Read instances faster, and make them fail fast
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        Reporter:  dfeuer            |                Owner:  dfeuer
            Type:  feature request   |               Status:  new
        Priority:  high              |            Milestone:  8.2.1
       Component:  Core Libraries    |              Version:  8.0.1
      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):
       Wiki Page:                    |
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Comment (by int-e):

 Replying to [comment:8 dfeuer]:
 > Replying to [comment:7 int-e]:
 > >     `chunkSize = 7 -- b^chunkSize must fit into an Int`
 >
 > Surely we should set the chunk size based on the actual word size,
 rather than assuming every machine is 32-bit or whatever.

 Yes, I intended to leave this as an exercise to the reader though, and
 instead focussed on streamlining the interesting bits of the algorithm.
 (In principle the chunk size could depend on the base as well, but only
 some serious benchmarking effort will show whether that is worthwhile.)

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12665#comment:9>
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