The ZeroMQ documentation suggests that you should use ZeroMQ to communicate between threads within the same process, as well as between processes. Given that context it wouldn't make sense for it to be thread safe. That would be too much overhead for no benefit.
ZeroMQ is very poor at communicating between threads within the same process, because messages are just binary data. The messaging library I use shouldn't dictate the way that I program; the dog wags the tail.
That would force me into an asynchronous style, but in my case, I was able to convey intent much better using threads.
This complaint is borderline non-sensical to me. Maybe Haskell is magic?
If ZeroMQ transported anything besides binary blobs, it would be marshaling objects or enforcing some kind of encoding to your data, which would dictate much more about your program. Are you upset that you had to use some Haskell.Vector to void* to Haskell.Vector code?
Are threads in Haskell not asynchronous by nature? Do you get synchronization for free somehow?
OK, in Haskell, data is immutable. If you want to pass data from one thread to another, there is no point in serializing it, sending it between threads and then deserializing it. You can just pass a reference. The data is also not typed, but that is potentially something you could fix in the bindings.
I know that in Erlang, you do pass data by exchanging blobs, but the difference is that Erlang has per Erlang-process heaps. Haskell has one heap, so there is no reason to do this.
It comes down to this, the way that you communicate between threads in the same process is different than the way that you communicated between processes.
> Are threads in Haskell not asynchronous by nature? Do you get synchronization for free somehow?
I'm not talking about what's happening underneath. I'm talking about the style that code is written in. I suppose, I could use a coroutine style monad over ZMQ's asynchronous API and create pseudo-threads, but they wouldn't get pre-empted, so you'd have to be careful to ensure that they didn't stave.
