Re: [Haskell-cafe] Simplest way to move a ... `using` ... line into the IO monad?

Thank you all for the quick replies! `mapConcurrently` was exactly what I needed. :) -db

On Oct 27, 2023, at 11:51 AM, Viktor Dukhovni wrote:

On Fri, Oct 27, 2023 at 07:43:07PM +0100, Tom Ellis wrote:

...

On Fri, Oct 27, 2023 at 11:36:53AM -0700, David Banas wrote:

...

What is the simplest way to translate a non-monadic line of Haskell code, such as:

res = map foo xs `using` parList rseq

For use in the IO monad?

This doesn’t work:

res <- mapM fooM xs `using` parTraversable rseq

The docs for Control.Parallel.Strategies say "The parallel tasks evaluated by a Strategy may have no side effects. For non-deterministic parallel programming, see Control.Concurrent."[1]. So I guess you should look into Control.Concurrent[2].

For a more friendly interface:

https://hackage.haskell.org/package/async-2.2.4/docs/Control-Concurrent-Asyn... https://hackage.haskell.org/package/async-2.2.4/docs/Control-Concurrent-Asyn...

If the number of concurrent tasks is reasonably modest, a good fit could be `mapConcurrently`.

For much larger numbers of tasks, it is best to run the jobs at a bounded concurrency, which may bring a BoundedChan to which the items to process are written, another to which results are written and a set of threads that do the processing, repeatedly reading more data until the channel is drained.

*The* book on subject is: https://simonmar.github.io/pages/pcph.html https://simonmar.github.io/pages/pcph.html

-- Viktor. _______________________________________________ Haskell-Cafe mailing list To (un)subscribe, modify options or view archives go to: http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe Only members subscribed via the mailman list are allowed to post.