You may hate me for this, but I'd recommend e-lisp. Why? It's got many of the advantages of scheme, and it's a language that'll treat you well the rest of you

You may hate me for this, but I'd recommend e-lisp. Why? It's got many of the advantages of scheme, and it's a language that'll treat you well the rest of your programming career (assuming you continue to use emacs). Also, the immediate feedback and lots of example source is pretty nice.