I've had a look at the changes to the modules wiki page [1]. I'm liking
the syntax changes quite a lot actually, but I have a couple of comments:
1) "export" ExportSpecifierSet ("," ExportSpecifierSet)* ";"
This rule seems too permissive. It allows strange combinations like:
export x, { y: a.b.c, z }, { j, k }, * from "bloop";
I think it would be better to flatten it out a little bit:
ExportDeclaration: "export" "{" ExportSpecifier ("," ExportSpecifier)*
"}" ";"
ExportDeclaration: "export" Identifier ("," Identifier)* ";"
ExportDeclaration: "export" "*" "from" StringLiteral ";"
2) Do we need `export *;`?
I don't see the point of exporting every declaration in the current module
scope. If the programmer wants to export a bunch of stuff, the other forms
make that sufficiently easy. Exporting everything encourages bad
(de-modular) design.
3) I'm just OK with "as". Note that it inverts the position of the string
and the binding:
import { x } from "goo";
import "ga" as ga;
Which makes it harder to read when you have a bunch of imports mixed
together. It's harder for the eyes to scan back and forth.
4) Why was this form eliminated?
import x from "goo"; // Note lack of curlies!
In an object-oriented application, we're often going to be importing a
single thing (the class) from external modules. So we may see long lists
like this:
import { ClassA } from "ClassA.js";
import { ClassB } from "ClassB.js";
....
import { ClassZ } from "ClassZ.js";
Removing the curlies for this simple case would seem like a win.
5) Dynamic exports via `export = ?` could make interop with existing module
systems easier. But how does that work?
6) Adding ".js" as the default resolution strategy:
I don't think this is tenable. First, there's the practical issue of what
happens when someone actually wants to load a resource without a ".js"
extension?
Second, there's the philosophical problem of essentially setting up an
alternate URL scheme. That's fine for libraries like AMD loaders or YUI.
But EcmaScript is a cornerstone of the internet. External resource
resolution can't conflict with HTML/CSS/etc.
- Kevin
[1] http://wiki.ecmascript.org/doku.php?id=harmony:modules
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