[Jtsummers]

> new concurrent primitives

You could make a case that concurrency primitives weren't mainstream in programming languages at the time. But there's not a strong case for saying that Go introduced new concurrency primitives unless you just ignore the history of programming and programming languages. Nothing in Go's concurrency model was new. Not quite mainstream, sure. But not new. [EDIT: By primitives I take you to mean built-in to the language, not brought in via libraries like pthreads or something.]

I'd also question the statement that "native binaries" were not mainstream. That seems to ignore a lot of code out there, including the C++ code that Go was (in part) meant to replace at Google.

Defer as syntax is maybe new? But some form of finally construct was in a lot of languages used at the time Go was developed. Defer flattens the code by reducing indentation levels, but it introduced nothing new in terms of concepts that weren't already being used by programmers of mainstream languages.

[scosman]

Faiiir. Nothing was net new concept. But the package they made was quite unique. Garbage collected but always native. No thread access, native channels and coroutines instead. Defer is pretty much net new in language design terms. No while loop?!? “If err != nil”!!? Lots of bold ideas, in a good package, and it worked so well. Calling the evolution boneheaded dismisses how hard it is to make so many opinionated bets in one go, and still make something successful.

[Jtsummers]

Just pointing out that it was not really as novel as you seem to believe it was at the time it came out.

> Garbage collected but always native.

Ok, sure. There were no other native garbage collected languages. Ignoring history, this is true.

> No thread access, native channels and coroutines instead.

If we ignore history again, also new with Go.

> Defer is pretty much net new in language design terms.

I can't think of an equivalent in the form of syntax, so sure. This is a point to Go. It's a small change, but useful for flattening code.

> No while loop?!?

I don't know why the exclamation mark. They have one named type of loop with `for`, but they definitely have a while loop:

  for x <= 10 {
    ...
  }

That's a while loop, it's not an infinite loop, it's not a do-while loop. That they reduced their looping constructs to one name (and then determine which actual loop kind by what's between `for` and `{`) does not mean they actually removed while loops. This does simplify the syntax, maybe.

> “If err != nil”!!?

[edit: missed this one]

  if (some_c_lib_fun(...) == -1) {
    // check the errno
  }

> Calling the evolution boneheaded

I didn't. Why are you putting this here?

[neonsunset]

defer is a poor man’s C# IDisposable (or even IAsyncDisposable)

    // The file handle will be freed at OS level when exiting current scope
    using var file = File.OpenHandle("somefile");

[Jtsummers]

defer is best compared to try/finally or unwind-protect and friends. You can defer any action, not just whatever the IDisposable happens to cleanup. It also gets access to the lexical scope for its deferred actions.

You could imitate that with IDisposable, but it would be overkill compared to just using finally (in C#).

[scosman]

^ thread