[GHC] #9332: Memory blowing up for strict sum/strict foldl in ghci

[GHC]

#9332: Memory blowing up for strict sum/strict foldl in ghci
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              Reporter:              |             Owner:
  artella.coding                     |            Status:  closed
                  Type:  bug         |         Milestone:  7.8.4
              Priority:  high        |           Version:  7.8.3
             Component:  GHCi        |          Keywords:  ghci, strict,
            Resolution:  fixed       |  memory
Differential Revisions:              |  Operating System:  Linux
          Architecture:  x86_64      |   Type of failure:  Runtime
  (amd64)                            |  performance bug
            Difficulty:  Unknown     |         Test Case:
            Blocked By:              |          Blocking:
       Related Tickets:              |
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Comment (by nomeata):

 Not a bug.

 `longList` is a CAF (e.g. a global not-yet-evaluated constant). When you
 load it in GHCi and evaluate result, GHC doesn’t know whether you are
 going to use `longList` again, and has to keep it in memory.

 But if you compile it is a program, or as a module only exporting `main`,
 GHC will make `longList` a local definition that, after the evaluation of
 `Result` is started, can be garbage collected. (With `-O` it will probably
 fuse it away even, but that is unrelated here.)

 But thanks for reporting!

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9332#comment:8>
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