Graham scan implementation in Common Lisp

[Trashtalk217]

I'm on a roll.

Generally happy with this one except the graham-scan function itself. It's not that clean and quite slow; nth and append are somewhat expensive. Otherwise I'm mostly good and I appreciate any review.

I messed up with git so that's why it looks so messy.

[berquist]

Can you do a rebase on top of current master to fix the conflict?

[berquist]

Very nice, just one comment on the consistency of implementations.

[Trashtalk217]

Basically as good as it's going to get. graham-scan Is still destructive because the standard sort is destructive in Common Lisp. But because sort only shuffles things around and the order of these things doesn't matter, I'm sure it won't matter that much. You could always pass a copy of the gift to the function ((copy gift)).

[berquist]

I'm sorry it took so long to get back to you. I think this implementation is really nice. Thanks for all your work!