[jaggederest]

The situation where it matters is with a trailing function argument, i.e.

    $ ->
      # do something on document ready
      $.ajax('path', options, (data) ->
        # do something with the results

Instead of

    $(->
      # do something on document ready
      $.ajax('path', options, (data) ->
        # do something with the data
      )
    )

Those trailing parens are ugly, and they're very common if you do event-oriented javascript via closures.

[stickfigure]

This is why our codebase uses paren-less calls when there is a trailing function argument, but uses parens in all other cases. It makes the code far, far more readable.

[jaggederest]

I agree, but I think making it a language restriction would be very odd. Coming from ruby, I also tend to think that this might be a nice way to do it, for things taking a final optional callback argument.

    $.ajax('path', options) (data) ->
      # do something with the data

But it does read less clearly, unfortunately.