What are your goals? Although the people here are pretty helpful, there isn't much out there, resource-wise, for Arc. This is both in terms of documentation and libraries.
Are you interested in hacking a Lisp itself? Then Arc is a good choice. Are you interested in learning a Lisp you can find companies using? Arc is suboptimal.
I suppose I'm learning lisp for more idealistic/philosophical rather than professional reasons. Though it seems there are compelling professional outcomes nonetheless.
I'd describe myself as a bottom-up thinker. [But I'm unopposed to the description "top-down" because . . . "which way is up?"] I like to work from axioms to outcomes. I'm frustrated under other conditions.
