Arithmetic evaluator for Guile

[No Itisnt]

Here's a little expression evaluator for Guile 1.9 using the new
bytecode compiler. It does arithmetic, exponentiation, modulos, and
equality tests. See the tests at the bottom for example expressions.
This is probably the most dense Scheme program I've written and I
would really appreciate a critique of the code.

http://pastebin.com/dhADj1EM