[Haskell-cafe] Re: derivation of mapP, a parallel, lazy map

Ben Franksen ben.franksen at online.de
Mon Feb 25 12:58:19 EST 2008

Dan Zwell wrote:
> Hello, everyone. I have just written a tutorial (sort of) on Haskell
> concurrency, 
> specifically on the derivation of a function mapP, a
> parallel version of map. I wrote this because I am fairly new to
> Haskell, and I didn't realize how easy concurrent code is until I wrote
> this, and because I could not find a tutorial describing a parallel
> implementation of map.
> If anybody is curious to see this, the page is
> http://zwell.net/content/haskell.html#mapP . I would appreciate any
> criticism, too. I hope somebody finds this helpful.

I have a criticism ;-) but it does not concern your page but above
highlighted part of your message: because you have /not/ written about
concurrency (and, gladly, I noticed that your page doesn't even mention the
word). Haskell's support for parallelism (about which you write) is
designed to /avoid/ (all the well-known issues of) concurrency. A tutorial
about concurrency in Haskell would have to mention IO, explicit threads,
shared mutable variables, etc... (which /do/ exist, as I assume you know).


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