I learned with Racket, and I found it to be a great experience. It comes with an IDE, DrRacket, that makes it very comfortable to start experimenting. It's al

I learned with Racket, and I found it to be a great experience. It comes with an IDE, DrRacket, that makes it very comfortable to start experimenting. It's also "batteries-included", with libraries for GUI, graphics, networking, etc. It also comes with really good documentation (at least as good as Python's, I'd say, and better than either Perl's or Ruby's). Racket has a good foothold in educational environments, so it's no coincidence that it's conducive to learning. However, Racket also sees a lot of usage in the PL research space, so it's also conducive to just experimenting. Those two combined can make it a very fun environment. There's also #racket on freenode, which I've found rather welcoming.