Out of curiosity, what makes you want to avoid significant whitespace? I think it solves the issue quite nicely. For what it's worth, I used to think SW was completely absurd. Then I spent a few years actually writing Python and have no desire to ever go back.

Python's requirement of indentation is somewhat limiting in terms of what the language can do. For instance, that's partly the reason why Python doesn't allow more than a single expression in a lambda.

It doesn't? Is there some kind of documentation about it we can look at?

Try: http://docs.python.org/dev/3.0/glossary.html#term-lambda

Sounds good that you are going to give significant indentation a try.

I like to have the flexibility to indent in whatever style the code calls for. That said, looking over the Python docs again, their implementation of significant whitespace is a lot more flexible than I remembered. I didn't realize you could do one-line method definitions, and that the whitespace only kicks in when you write a multi-line block.

Here's a question for you. In Python, if you have a couple of nested lambdas with multiline bodies, getting passed into each other as arguments, do you have to write the closing parenthesis on the correctly-indented line on the other side, or can it be tucked against the inner lambda?

In a hypothetical significant-whitespace CoffeeScript, I'm thinking of this:

    elements.each(el =>
      el.click(event =>
        el.show()))

Versus this:

    elements.each(el =>
      el.click(event =>
        el.show()
      )
    )

Is the second form required to make Python-style whitespace work?

Python does not have multiline lambdas. But Python only uses significant whitespace when it can't use other demarcations. For example, the following is legal:

  a = [
        1,
          2,
            3]

No.

Great. Then let's start a "whitespace" branch, and give it a go.

Edit: Alright, got a branch that starts with a little significant whitespace going here:

http://github.com/jashkenas/coffee-script/tree/whitespace

It can't handle the first of the two cases mentioned above just yet, but it compiles the second one correctly.

I actually think that the period to end blocks syntax is one of the most interesting things about it. It's such a small thing, but i find it quite intriguing.

Its quite pleasing; well done!

My take on the blocks is that significant whitespace seems to be a natural expression of blocks for your language and fits quite nicely with the aesthetics of the other forms. (The terminal ... choo choo train is not a winning idea.)