[gngeal]

C#5 added async/await, which I think is one of the most 'integrated' ways I've seen of doing async programming.

What's with the C# developers ans async/await? Almost every time I read their exhortations it feels like they're blissfully unaware that other languages have already had their own mechanisms for doing concurrency.

[sitharus]

Having worked in a few languages over the years, all with different ideas of concurrency, the C# system is one of the nicest.

It's a bit tough to get your head around, but it does a good job of keeping code readable while correctly blocking and descheduling threads.

A lot of developers get async wrong, so anything to help get it right is a plus.

Personally I prefer the F# async system, but it's harder for a curly-brace developer to learn F# than a new C# keyword.

[stevecooperorg]

We're talking languages here; the way a grammar construct helps the programmer.

The C# async language effectively writes a whole batch of code that you'd need to write yourself in other languages; try/catch blocks, callback functions, thread synchronization code, code to wait for results, etc. In effect, it makes into a language feature something that has previously been considered a design pattern.

So something like this in C# 5;

    01 var foo = await LongProcess1();
    02 var bar = await LongProcess2(foo);
    03 var baz = await LongProcess(bar);

does a significant amount of work. If I were to code it without the language support, I'd be writing a great deal of crufty code to handle errors, to make sure one thread completes before using the result in another thread (see foo set on line 01 and used on line 02 for an example) and it avoids the callback hell problem of languages like JavaScript, which become apparent in Node.js programming, for instance.

I'd be interested to know what other mainstream languages have as complete a solution for asynchronous programming -- afaik, JS, Python, Ruby, Java, and C++ don't have this. I'm guessing erlang probably has it built right in, but I'm not sure. Anyone care to share?

[gngeal]

We're talking languages here; the way a grammar construct helps the programmer.

So do I. We've had CSP, Occam, Newsqueak, Alef, Limbo; now we have Erlang and Go. I'm just puzzled by the walled garden phenomenon present in such communities as that of the .NET programmers. The very fact that you're comparing C# to Node.js (!), of all things, just confirms it. It isn't very difficult to beat Node.js in terms of the language quality. Hardly seems like a fair fight to me.

[stevecooperorg]

It's hard for me to see how I'm living in a walled garden here. If there is a Microsoft walled garden, Hacker News is very much outside the wall, isn't it? I'm here, not on MSDN, trying to have a reasoned conversation with intelligent people from different backgrounds, showing code samples, and asking openly for information about other languages. What else should I be doing?

> The very fact that you're comparing C# to Node.js (!), of all things, just confirms it.

The node.js comparison is fair, I believe. We're talking about language support for asynchronous programming, particularly the evented I/O programming idiom. That's exemplified by C#/await, and the Node standard libraries, and python/twisted, and I'm sure a lot of others.

Node is a very popular, visible platform which takes evented I/O as a core concept, so it's reasonable to compare the implementation of the idiom in C# to the current poster child. Is there a better comparison I missed?

> We've had CSP, Occam, Newsqueak, Alef, Limbo; now we have Erlang and Go.

Agreed. That's fine, and I specifically called out Erlang and asked for more info. However, the others you list suffer from not being mainstream development languages -- TIOBE[1] doesn't list any of them in the top 50 languages. Occam may well do it better, but since I can't pay the bills writing Occam, I'm more interested in the languages I mentioned -- JavaScript, Python, Ruby, Java, and C++. Feel free to throw in C, PHP, Perl or Objective-C. Do any of these languages have better language or core library support for async programming? Do they result in shorter, more readable, or more reliable code for parallel and async operations?

Your original reply -- "Almost every time I read their exhortations it feels like they're blissfully unaware that other languages have already had their own mechanisms for doing concurrency." -- suggests I'm unaware of something. Can you please start telling me what it is.

  [1] http://www.tiobe.com/index.php/content/paperinfo/tpci/index.html
  [2]: http://www.paulgraham.com/avg.html

[MichaelGG]

Because it allows a nice syntax for async callbacks, instead of callback hell like JavaScript and C# APIs prior.

[statictype]

Built-in to the language itself?

Very few mainstream languages have that.