My problem right now: fn((a b)) could define a function that takes a list of two args, or an optional arg a with a default value of b bound in the enclosing scope. This seems like a more serious problem than when I posted this thread.
Though (for what it's worth) I've since realized that I don't like the {a 1 b 2} syntax; I find the key value pairs aren't grouped together well enough visually for me, and the curly brackets don't stand out enough themselves.
