I'm not entirely convinced with the function-call syntax for declaring a Symbol.
Why not using something more of the lines with Ruby's :symbol syntax?
Why not using something more of the lines with Ruby's :symbol syntax?
You can't go around peppering your code with use of this new syntax if you want it to continue working on older runtimes. With `Symbol`, you can at least create a polyfill that approximates what it's shooting for.
> declaring a Symbol
Don't think of it as "declaring a symbol" (because it isn't). Think of it as generating a symbol (because it is).
Who really wants to write map.add(new Symbol("foo"), 'bar') instead of map.add(#foo, 'bar')?
It makes it clear when you are generating new symbol, and when you are reusing existing symbol.
var a = new Symbol("foo");
var b = new Symbol("foo");
map[a]="firstValue";
map[b]="secondValue";
Console.log(map[a] + " " + map[b]);
// writes "firstValue secondValue"
map[#foo]="firstValue";
map[#foo]="secondValue";
Console.log(map[#foo]); // what is written here?Nobody because it's completely daft, and absolutely not equivalent to the second version, the equivalent to the second version is:
map.add("foo", "bar")In particular object[:symbol] would behave quite differently (and would be probably worthless since everytime you would access a new property ).
It would make more sense to have :symbol a shortcut for Symbol.for("symbol") instead, but I don't think it would be that much useful.
Because Ruby's symbols are completely different and designed to collide. A Ruby symbol (like an Erlang atom) is a very cheap immutable string-like structure but :symbol is :symbol.
A Javascript symbol is (as others noted) much closer to a lisp unique symbol (the output of `gensym`), and having it be a function is perfectly fine since you have to keep it around anyway (or you can't access symbol-named properties).
Symbol.for is roughly equivalent to :symbol, but the use case for it is much more limited and there's really no reason for a literal version./
You mean Common Lisp's syntax, of course.