> So there you have it. Not type error, nor the one and only output when an expression is evaluated. (not S-expression)
Yeah that's pretty much what I was going for, except better-written. By "a value" I was referring to that specific value -- either 't' or '+' (which, in this case, also printed 't').
I have read SICP, and I believe it is a first-level book, so long as you understand the underlying mathematics. Not so good for students who are still trying to figure out derivatives.
Anyway, welcome to 4-ch, I'm pretty sure you'll like it here. Just do less trolling. ;)