Comments on: 0MQ and Haskell

By: Dag

Dag — Thu, 22 Mar 2012 15:44:10 +0000

You know forM_ = flip mapM_ right, just trying to spare an import?

By: Mark

Mark — Sun, 11 Mar 2012 12:51:13 +0000

@Magnus not yet, it's still at a very early stage. We can successfully receive and send messages, but we haven't got proper support for the different socket types. I'm a bit torn here, actually - the C implementation uses a state machine to model the allowable patterns (ie, a REQ socket has to send then receive in strict alternation, and vice-versa for a REP socket) - it feels like something we ought to be able to model in the type system in Haskell.

Interestingly, I've found it changes the way I write C much more than the way I write Haskell. The appeal for Haskell is in being able to interoperate with other runtimes, i think: if you just wanted intra-process coordination, you already have cheap threads and MVar/TVar/STM etc.

By: Magnus

Magnus — Sun, 11 Mar 2012 08:38:15 +0000

@Mark, Cool, do you already have some numbers comparing your pure Haskell implementation against the FFI implementation in zeromq?

By: Magnus

Magnus — Sun, 11 Mar 2012 08:29:11 +0000

@anonymous, indeed, I’d love reading something like that too. Have you started writing it yet?

By: Mark Wotton

Mark Wotton — Wed, 07 Mar 2012 08:49:39 +0000

Xavier Lange and I have been working on a pure Haskell implementation of 0MQ too. I’ve been using the binding pretty heavily, but there are some things you can’t do directly with it. Still, it’s exciting technology, I’ve put a large part of ninjablocks.com’s back end onto it (albeit using ruby) and I’m looking forward to shifting more of it to Haskell.

http://github.com/ninjablocks/zmqhs (at least until Xavier pulls my changes in)

By: anonymous

anonymous — Wed, 07 Mar 2012 04:53:53 +0000

I’m not sure why, but the Haskell client dies after receiving just a few messages (they are properly filtered though).

Someone should write a blog post where they successfully debug a problem like this. That would be a pretty interesting display of real world Haskell and its development tools.