expression expansion within a string

[nyuichi]

The syntax may subject to change.

var num = 42;

var str = """
abc
#{num}
def
""";

[gfx]

Looks good to me except for the symbols. Because I'd like to use it in single-line string literals, the quote symbols must not be double quotes or single quotes. Back quote (`) is a candidate; triple backquotes are used for code sections in markdown, though.

In addition, we have reasons to avoid # for interpolation: # is used for comments in some programming languages and also used for level-1 header in markdown, which might be confusing, so we'd better to use another symbol, e.g. $.

[nyuichi]

@gfx

Back quote (`) is a candidate; triple backquotes are used for code sections in markdown, though.

So you mean you like to write like this?

var str = "abc `{num} def";

In addition, we have reasons to avoid # for interpolation: # is used for comments in some programming languages and also used for level-1 header in markdown, which might be confusing, so we'd better to use another symbol, e.g. $.

I don't prefer $. It's too perlish.

[gfx]

No, I mean:

var str =`abc ${num} def`;

And $ is not from Perl, but from shell script. In fact, the use is more alike from shell's.

[kazuho]

Re quote, +1 to using '`'.

Re substitution marker, IMO we should choose a character that is (or will become) familiar to ECMAScript programmers. So if the Quasi-literal of ES5 is going to use '$' then we should use it, or if not, we should use '#' (since that is the character used by CoffeeScript and TypeScript?).

[gfx]

TypeScript does not have string interpolation; there is a discussion found in ITS, though: https://typescript.codeplex.com/workitem/19

ES6 is also considering to use $ http://wiki.ecmascript.org/doku.php?id=harmony:quasis ; I don't know it very well.

Dart also uses $ for interpolation: https://www.dartlang.org/docs/dart-up-and-running/contents/ch02.html#strings

I gues this is because # is used for location hash and CSS selectors so not suitable for HTML applications.

[kazuho]

If the majority are heading towards using '$' then we should jump on the bandwagon as well.