"Looks pretty good though I'm not so sure about the double enter requirement."
It's not just wart: readable has the same issue. The problem is that you don't know if the user is finished or if they want to enter a multi-line expression. With parentheses, you always know whether the expression is completed or not, but with whitespace, you don't.
The same is true even in Python. If you type in this:
>>> def foo(x):
... return x
You have to hit enter twice. In some cases, Python is smart enough to know that the expression ended, so you only have to hit enter once:
>>> 1 + 2
But that's because Python's grammar is more restricted in certain areas. That doesn't work with S-expressions because they're so general.
I realized after I'd read wart's readme that parens were optional, though I don't think that would have been enough to clue me in on the double enter requirement. :)
Yeah, I didn't expect everyone to remember that :) I just wanted a sense of whether the no-prompt prompt was intuitive. So far it seems to be intuitive!
