But let's go look at patterning: look at Node: everything is hinged around re-using Node's core patterns, callbacks and every now and then slower events. There is promises work abound, but it's not used heavily: indeed it'd be hard to, with intermodule work, because A) it's not the standard lib B) nor are promises standardized. People seem to prefer something I loath- the horrible Async library- which gives them a bunch of composition tools to make worse the awful awful crime that is callbacks: because callbacks are what Node is, people pick up tools to do it more, to a further extreme, rather than going to the foundation & reshaping the landscape. (PS: Callbacks are A) awful B) actually & entirely the right decision.)

I was reasonably seriously into Perl, but I don't know what perl CSP style library you seem to be alluding to that A) you seem to indicate people used & B) got on par with Go 10 years ago. But I'm interested to hear of it! <3 me some CSP.

I wouldn't have said anything if I didn't disagree very strongly with these sentiments (see below about growing your own CSP/etc, and later about Coro in particular.) But first, about Node: let's not look at Node (unless you really want to, but as long as you understand it has nothing to do with my comment.) Problems with JS are usually founded on people complaining they don't like callbacks (translation: "Go is better because I like it better"—in which case please dispense with the cognitive dissonance and just be honest and say as much♯) and are inapplicable to other most other languages regardless.

♯Edit: That's not necessarily directed specifically at you, but people often vilify every aspect of things they don't like. I'm not convinced that's what you're trying to say about JS.

I don't view concurrency as this mysterious thing, if you know CSP you can write it in any language, usually fairly naturally. In languages like JavaScript, Perl, Tcl, you can even make it look like it was already part of the language, tucking away calls to the scheduler so the user doesn't need to write them explicitly (heck, you can do that part in C... but... don't), like in Go (save for pure-computation loops, also just like in Go.) All Go really does over the general case is adding implicit calls to the scheduler (not nicely possible in some languages) and treats the scheduler as a second-class primitive feature.

To go on about a unified implementation reaches my ears much like an argument that you'd better use `for` loops and never `map`s (guess what you can't do in Go.)

I wasn't going to bring this up, but since you're familiar with Perl you will be less likely to assume limitations. The lib is Coro. People do use it, but it is controversial because of #dramaintheperlcommunity (#whatelseisnews.) I don't know how popular it is overall, but if popularity is an issue for you let me know because it's a stupid argument to get into and I don't want to have it without realizing it. People rarely pay attention to concurrency anyway, but it's been around forever.

It is not a parallel library, for which I am thankful. (It's not incompatible with parallelism, and importantly: it doesn't make Go's mistakes in that area.) It amounts to a scheduler, facilities for spawning coroutines, wrappers to make calling the scheduler implicit (eg. at IO points), do async IO and every single thing you would need to make Perl automatically do the things Go automatically does. It will look exactly like Perl with Go's concurrency model, in broad strokes you do the same things, in the fine details you use Perl modules and methods and a new keyword or two.

If you don't know CSP you still have no choice but to write it in Go: that the core unity I've been trying to describe, something the entire standard library is built around, like callbacks in Node. I don't see that you've added anything to your case for other languages in this recent reply: I think this excerpt captures well how your line of thought remains focused on what is possible, while ignoring my core arguments that it's all about the prime interface of the Turing machine before one, not what they set up for themselves on the machine.

"In languages like JavaScript, Perl, Tcl, you can even make it look like it was already part of the language,"

And newcomers may be able to immitate/cargo-cult your styling blindly without straying too far off the gods-sworn path if they are really lucky!

But rather than risk it, making a language CSP first would, IMO, be a clearer way to keep unity.

I really don't care what can be done with a Turing complete machine: I care what use of that machine looks like to the important audience: it's practitioners, all of them, practiced and experienced, and those with other backgrounds and seeking only practical results.

Go has created an entire language all of whose practitioners trade in CSP. I'm happy to de-rate from a language to a massively successful widely known active (let's say +30k active developers) shared and intercompatible practice of doing CSP (libraries or what not). Until I hear that challenged, my argument about Go being fundamentally different for having a runtime and standard lib based around CSP stands untouched, unless you have something specific there to contend.

I guess they should count themselves lucky if they know what an API is at all. C'mon this is a 101-level topic. You can't expect everyone to suddenly forget how to use an API (with or without native syntax) just because it's for concurrency... or do you?

As for Coro, it doesn't matter how many people use it, you can write the exact same things you would write in Go and it will work in the exact same way. It's not cargo-culting, it's writing CSP, which you still have to actually write CSP in Go if that's what you want, and it's perfectly possible not to.

The runtime distinction isn't very important either, in fact when I hear "runtime" I ask "why not library?" Some things are impossible in libraries but CSP is not among them, so I'm still asking "why not a library?" The scheduler, probably the most interesting part, can always be implemented as a library. Can you say anything particular to Go's runtime that makes it so special? I can't think of a single thing. The scheduler itself is about as boring as it gets. Not that there's anything wrong with that—it's not a difficult subject after all.

As for the popularity contest goes, we might as well be talking about an iteration protocol. There are many different ones but you'd rarely notice it. The most commonly used ones are relatively less-than-great. You can always use a for-loop like you can always write a coroutine or time slicer in the worst case scenario. It works, and very well.

The other thing is CSP. Up to now, I wasn't worried about the concurrency model in particular, but now you're saying we can't use actors, agents, etc.—it must be CSP. That's BS. CSP is nice when you have to build it yourself, but it's not all there is and it's no easier to reason about than other good options. In fact I would mostly only chose it when I had to build it myself or support for something else wasn't available, which is understandably common. Really though, this sounds like a deceitful way to rule out Erlang and friends.

    And newcomers may be able to immitate/cargo-cult your styling blindly without
    straying too far off the gods-sworn path if they are really lucky!

  I guess they should count themselves lucky if they know what an API is at all.
  C'mon this is a 101-level topic. You can't expect everyone to suddenly forget how
  to use an API (with or without native syntax) just because it's for concurrency...
  or do you?

  As for Coro, it doesn't matter how many people use it, you can write the exact same
  things you would write in Go and it will work in the exact same way. It's not
  cargo-culting, it's writing CSP, which you still have to actually write CSP in Go
  if that's what you want, and it's perfectly possible not to.

I don't know about you, but most of my work is not writing code: it's using code. You miss this essential fact again and again.

What is possible is entirely not at all my interest here. I am interested in the practice of writing code. My sole contention against you is that the availability of libraries is irrelevant, an my basis for this point is that I agree with:

  The runtime distinction isn't very important either,  [[snip]]

  in fact when I hear "runtime" I ask "why not library?"

And every time you've gotten a response that agrees with your conjecture that it might be possible!

So why are you still making this same uncontested assertion!

So maybe you need to find something else to do, other than to re-describe how possible libraries make it to be Go-like or otherwise concurrent, because- with some niggling performance issues- there's been naught but agreement, and you've avoided clashing every time with my fundamental point that Go has a practicing community with some many thousands of libraries written for it, and the libraries you are talking about don't, and using your libraries will create a schizm between you and the other practioners of the parent language and the modules written for it, and Go users have no impedance when working with one another w/r/t their concurrent systems.

  Some things are impossible in libraries but CSP is not among them, so I'm still
  asking "why not a library?" 

  The scheduler, probably the most interesting part, can always be implemented as a
  library.

  Can you say anything particular to Go's runtime that makes it so special? I can't
  think of a single thing. The scheduler itself is about as boring as it gets. Not
  that there's anything wrong with that—it's not a difficult subject after all.

  As for the popularity contest goes, we might as well be talking about an iteration protocol. There are many different ones but you'd rarely notice it. The most commonly used ones are relatively less-than-great. You can always use a for-loop like you can always write a coroutine or time slicer in the worst case scenario. It works, and very well.

  ???

  Please cite where I went hardline and demanded CSP as the only acceptable communications/concurrency primitive I'll amend that such that your argument here is thoroughly unnecessary- I certainly don't see myself as opposing what you are saying, but you didn't actually tell me what the clash was that arose this contention- all you said was "The other thing is CSP. Up to now,"- and that doesn't actually inform me about what changed your mind, & made you think I was hardlining for any specific thing; so, I'm not sure how to clarify and reinforce my agreement with you, and my willingness to embrace any practioner's use of good solid helpful concurrency construct, be it of the communications variety (which I do myself enjoy, as concurrency in my artisan's mind is modeled as non-locality) or otherwise.

I see you didn't look into Coro or read much of what I said. You do IO in the regular way and the scheduler is automatically invoked.

(If you want to know what needs wrapping, just use your head. If it does IO, make sure you have that kind of IO wrapper. If you screw this up your program will still work.)

You are a masterful troll sir. The runtime itself is not novel.

You yourself stressed the importance of the fundamental difference in the Go runtime, two or three times I believe. It seemed to have something to do with your argument against libraries.

The one argument you claim to have left (userbase) is the one you've been ignoring my comments about since the beginning. I'm not interested in arguing it anymore, but if you're interested in it, feel free to re-read my comments on that matter.

Using only ready, cede and schedule to synchronise threads is difficult,

Coro supports a number of primitives to help synchronising threads in easier ways.

Coro adds threading to Perl but falls short of being a concurrency practice- it's tooling for doing concurrency.

Go establishes two fundamental primitives, goroutines and channels, and gets rid of old-worn notions of threads.

This isn't a novel runtime, because it's been done- in Newsqueak, just to name one- but the entire platform built from the ground up to be mobilized around not giving you the tools to find your own concurrency solutions, but to have a deliberated answer to all concurrency problems, a masthead banner saying "THIS IS THE ANSWER" is the differentiation and novelness I'm ascribing to Go.

That approach, over our discussion, I've come to realize is more characteristic of the standard library of Go than it is the runtime. That said, you're holding my feet awfully cruelly to the fire and I take issue with you using this newly gained outlook in such a mean-spirited and cruel fashion to stab at me.

Talking with you is incredibly frustrating as you toss away my points with a single dismissing wave and do not cite material things; you pick tiny little fragments to quip at as springboards to launch into whatever you wanted to start talking anyways. As I said before, masterful trolling, it's very hard to hold a conversation with you. I'd beg of you to yield, because otherwise we might indeed find ourselves on the field of Ragnarok, at that end that never comes after all infinity.

You also seem very ill informed about Coro- which you champion-

Fortunately, the IO::AIO module on CPAN allows you to move these I/O calls into the background, letting you do useful work in the foreground

So, no, _You do IO in the regular way and the scheduler is automatically invoked_ is a bullshit claim; this has all the weaknesses of Node.js's event loop, and the need to write small things that yield, or here in Coro world, cede, regularly. And if you use a CPAN module that does block, you are toast, making this fundamentally incompatible with everything else ever done in Perl in a very serious way.

a simple module that implemented a specific form of first class continuations called Coroutines. These basically allow you to capture the current point execution and jump to another point is in no way a parallel to the runtime of Go because the stdlib of perl is not meant to operate in a non-blocking way, and Go is. That, I think, is safe to say.

On the contrary, I've used it. And Go. I know what it's like in practice which do not, and this makes your claims sound very ignorant to me.

So, no, _You do IO in the regular way and the scheduler is automatically invoked_ is a bullshit claim; this has all the weaknesses of Node.js's event loop, and the need to write small things that yield, or here in Coro world, cede, regularly.

This is proof of your ignorance. It isn't like working with an event loop (but it is compatible with them, ultimately giving you a better option for parallelism than Go.) I was going to mention how rarely `cede` is necessary, but I had honestly forgotten what it was called. You need it exactly as often as you need to write `sync` or whatever it is in Go. Seriously, you can write the exact same program as far as where and when calling concurrency facilities are and you will get the exact same concurrency profile in your program.

I'm not sure what you think the wrappers are for, but they introduce non-blocking behaviour into the library calls you make by, as I've said a few times now, invoking the scheduler—that's how this all works after all. There's no compatibility problem either, that's BS you came up with like just about everything else you've said about it.

The best part is when you say it's just a GOTO that doesn't do anything about synchronous long running code problems—how do you think Go's concurrency actually works under the hood? It works the same way—and has the same problem you describe.

_how do you think Go's concurrency actually works under the hood? It works the same way—and has the same problem you describe._

I think Go, in most uses, makes use of a thread pool to decouple it's green threads from the OS threads such that a single busy green thread does not seize up the rest of the runtime, and I think Go manages the assignment of green to OS threads in a way that is hands off for the programmer and by default.

I also think one gets a runtime in Go where I/O is multiplexed on an event loop, such that most common syscalls a Perl program might make don't hold up execution, and are instead handled in a non-blocking way by default.

Please let me know what else I can clarify so that we can find agreement.

I'm not sure what's left to clarify on your part. I think you misunderstand what working with Coro is like. In practice the Perl code that holds up execution is the same code that holds up execution in Go, things like:

    while(1) { $i++ }

I'm not sure what there is to agree on. I could perhaps eventually convince you that working in Coro is very much like working in Go, or you could do that on your own time if you really want. But you seem to have an issue with a concurrency implementation that isn't widely popular, and that sounds like a matter of taste to me. To my ears it sounds like an incredibly stupid thing to get hung up on—CSP is so easy—but if that's your bag I'll only ask you not to use it to convince me of anything.

Concurrency is the root of all code construction, at a more meta- level than writing code. Layering it in with libraries is feasible, but you've already imposed some structure from the code, then you're adding on top of that structure an underlying structure, and that's... well... that's something Go avoided doing.