[Haskell-cafe] parallel Haskell

[Rein Henrichs]

Please take a look at Simon Marlow's free book, *Parallel and Concurrent
Programming in Haskell* (http://chimera.labs.oreilly.com/books/1230000000929).
It will teach you a lot about... the things in the title.

On Thu, Jul 6, 2017 at 10:21 AM Claude Heiland-Allen <claude at mathr.co.uk>
wrote:

> Hi Dennis,
>
> On 06/07/17 17:53, Dennis Raddle wrote:
> > I have a program which does backtracking search in a recursive
> > function.  I followed the chapter in "Real World Haskell" to parallelize
> it.
> [snip]
> > There's no effect from the R.W.H. ideas. Can I get some suggestions as
> > to why?
>
> You can get timing and other useful diagnostics by compiling with
> -rtsopts and running with +RTS -s, no need to measure CPU time in your
> own program.
>
> > force :: [a] -> ()
> > force xs = go xs `pseq` ()
> >   where go (_:xs) = go xs
> >         go [] = 1
>
> This force doesn't do enough, it just walks the spine. Try this, which
> forces the elements as well as the shape:
>
> force :: [a] -> ()
> force xs = go xs `pseq` ()
>   where go (x:xs) = x `pseq` go xs
>         go [] = 1
>
> Thanks,
>
>
> Claude
> --
> https://mathr.co.uk
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