Re: A few more questions about the current module proposal

Right - Sam's example of having a specific CoffeeScript loader isn't going to actually work for this reason.  Instead, we'd have to figure out which "to-JS" compiler to use inside of the translate hook.

    let maybeCoffeeLoader = new Loader(System, {

      translate(src, relURL, baseURL, resolved) {

        // If file extension is ".coffee", then use the coffee-to-js compiler

        if (extension(relURL) === ".coffee")

          src = coffeeToJS(src);

        return src;

      }

    });

You could use the resolve hook in concert with the translate hook to create AMD-style plugin directives.  It looks pretty flexible to me.

One question, though:  branching on the file extension, as above, will not generally work.  The source code might be served through a URL that does not have a file extension.  On the web though, we'll generally have access to a Content-Type header.  In the current design, there's doesn't appear to be a way to get that information.

One possibility for getting the Content-Type header would be to override the fetch hook and use cross-domain XHR, but that seems like a lot of duplicated code just to get data that's already being received by the browser.

Thoughts?

- Kevin