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Comment by tuxychandru | Hacker News Reader

Rust's multi-threading most certainly is not CSP. CSP requires communication to be synchronous. Rust documentation states that send() will never block and channels have infinite buffer.

AFAIK, rust also doesn't allow selecting between a send and receive on channels. It only allows selecting over a set of receivers and even there it doesn't offer something like the default clause of Go's select statement.

Rust does have interesting features to prevent data races but it's concurrency model is very different from CSP and Go. Since the author praises Go's concurrency in the context of writing servers, it is entirely reasonable to prefer goroutines over OS threads as the unit concurrency.

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Rust supports both synchronous and asynchronous message passing over its channels. It's true that asynchronous message passing is generally associated with actor systems and not specifically with CSP, but it's also seen in many extensions of CSP, and in fact CSP and actor systems are duals of each other.

Rust supports both approaches.

I was wrong about synchronous communication. Since most rust example use async channels, I missed the existence of sync_channel.

However, even if that exists, rust's concurrency doesn't follow CSP as much as go's. Like I mentioned in my previous comment, it doesn't have a way to do everything the select statement in go does. This is not necessarily a bad thing, but rust definitely doesn't share the same concurrency concepts as go. It offers everything that Java/C++ does along with data race protection.

Speaking of data race protection, the current type system rejects a lot of very common "non-racy" code too. There is work in progress to address some of them and may be most of them will be addressed eventually.

> doesn't follow CSP as much as go's

Because it supports asynchronous messaging too? As if CSP were some concept that emerged fully formed from Tony Hoare's head like Athena from Zeus?

I'm sorry you see dichotomies where others see dualities.

I was referring to select statement, not async messaging support.

You mean like the select! macro in Rust?

No the select statement of go. It is way more capable that rust's select macro.

The tone of your previous comment made me feel that this thread is going in an unproductive direction, so I'll stop here.

Considering you've backpedaled from "Rust isn't CSP" (because you misunderstood Rust channels) to "Rust doesn't have select" (which it does, and you didn't realize) to "Rust's select isn't as mature as Go's", that's probably for the best.

Perhaps you should try to be more informed about Rust before you try to have an argument about it in the future!

I said 2 things in very first comment. I never claimed rust doesn't have select. This is quoted from my very first comment in this thread,

Perhaps you should try to read my comments in their entirety before making accusations.

Yes I missed sync_channel, but if that is all CSP was, Java does CSP too. It has Threads and SynchronousQueue exactly like rust 1.0 will.

I thought you were done? Apparently not!

This is where I again point out that neither Java nor Go ensure that state sent over channels is actually isolated, and both allow data races.

With Rust that is not the case. You have true isolation (unless you explicitly opt not to)

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