[pcwalton]

> Go's lexical scoping and first class function/method's owe a lot to JS for leading the way IMHO.

I don't think this comment deserves the downvotes. JS deserves a lot of credit for doing scoping right in 1995, at a time when most popular languages (i.e. not Lisp or ML) were doing it wrong. (A notable exception was Perl 5, which did scoping right in 1994.) Thanks to JS, a lot of working programmers who would never be exposed to Lisp learned lexical scope. Remember that Emacs Lisp famously chose dynamic scope over lexical scope (a serious blunder) due to RMS's belief that lexical scope couldn't possibly be implemented in a performant way!

[rsc]

I argued for the design of and wrote the implementation for Go's lexical scoping and first class functions, and I can tell you they were in no way influenced by Javascript.

Scheme, Lisp, ML: yes. I'd written sizable programs in each of those, I'd worked on rewriting a programming languages course textbook with a professor in college, and I'd studied On Lisp. One of the initial test cases was Paul Graham's accumulator generator: https://github.com/golang/go/blob/0f4f2a6/test/closure.go

Javascript: no. At that time (Feb 2009) I doubt I even knew Javascript had lexically-scoped closures. I know I didn't buy 'Javascript: The Good Parts' until March 2010. Even today I don't think the fact that Javascript got closures right is particularly remarkable, except that, as Crockford demonstrates, that fact serves as the fundamental saving grace that enables forgiveness of many other problems.

[pcwalton]

I wasn't suggesting that JS directly influenced you. Rather my point was that JS was of the most important languages that brought lexical scoping and closures to the masses. By the time Go came around, it was considered a bog-standard feature, because of languages like JS (and others) that popularized it. That meant that programmers could more easily pick up Go.

[donatj]

Even if JS was not in the back of your mind, you have to admit that the design of "LISP in Cs clothing" (to quote Crockford) turned out nearly identical - certainly much closer than to Scheme, LISP or ML. And JS did it much earlier than Go. My point was that it owed developer comfort with the design to JavaScript, and not necessarily direct design influence.

[muflax]

What languages without lexical scope are you thinking of?

Aside from literally only (pre-Common and Emacs) Lisp, I can't think of any language without lexical scope (outside some constructs etc).

[edit:] Or are you thinking of "only a single global namespace"? Even that exists only in otherwise highly restricted scripting languages, I think? ("Everything global" is technically lexical, but I see why you wouldn't want to call it that.)

[pcwalton]

Tcl, PHP, any language without closures.

[muflax]

How does PHP have dynamic scope? It's been ages since I touched it, but if I remember right...

Global is just a flat namespace. Functions have their own, separate flat namespace each. I tried the following in a REPL:

function two() { echo $a; }

function one() { $a = 1; two(); }

one();

as the standard dynamic scope example, and I get an "undefined variable" error. Did that use to be dynamic? (I wouldn't be surprised, though, especially given PHP's implementation history...)

There is an explicit "static" modifier that looks dynamic, but I couldn't get it to run that way. It seems to just retain state in recursive calls of the same function, or something?

[edit:] (And PHP doesn't predate Javascript, but regardless, "no first-class functions" isn't "no lexical scope".)

[pcwalton]

Yeah, I shouldn't have used the term "dynamic scope" there. PHP has dynamic environments that can be mutated at runtime, which languages like JS don't (well, outside of direct eval).