Several of the monad-par schedulers COULD provide a MonadIO instance and thus "liftIO", which would make them easy to use for this kind of parallel IO business:
http://hackage.haskell.org/packages/archive/monad-par/0.3/doc/html/Control-Monad-Par-Scheds-Direct.html And that would be a little more scalable because you wouldn't get a separate IO thread for each parallel computation. But, to be safe-haskell compliant, we don't currently expose IO capabilities. I can add another module that exposes this capability if you are interested... -Ryan On Fri, Sep 28, 2012 at 4:48 PM, Alexander Solla <alex.so...@gmail.com>wrote: > > > On Fri, Sep 28, 2012 at 11:01 AM, Greg Fitzgerald <gari...@gmail.com>wrote: >> >> >> I also tried Control.Parallel.Strategies [2]. While that route works, >> I had to use unsafePerformIO. Considering that IO is for sequencing >> effects and my IO operation doesn't cause any side-effects (besides >> hogging a file handle), is this a proper use of unsafePerformIO? >> > > That's actually a perfectly fine use for unsafePerformIO, since the IO > action you are performing is pure and therefore safe (modulo your file > handle stuff). > > unsafePerformIO is a problem when the IO action being run has side effects > and their order of evaluation matters (since unsafePerformIO will cause > them to be run in an "unpredictable" order) > > One common use for unsafePerformIO is to run a query against an external > library. It has to be done in the IO monad, but it is a "pure" computation > insofar as it has no side-effects that matter. Doing this lets us promote > values defined in external libraries to bona fide pure Haskell values. > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > >
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