# [racket] Capturing Procedures in Macros: Style Question

Hi everyone,
I wrote a small polynomial math library. In it are operations like
poly-add, poly-times, poly-expt, and poly-sub, performing the
operations that should be obvious. In a language like C++, one might
have defined a polynomial class and then, possibly, override the +, -,
and * operators (and throw up about the expt operation). I'm not
normally a fan of operator overloading in a language because I feel it
obscures what's actually happening. But in a language like Racket,
overloading for a particular scope can be explicit and it seems less
like encryption and more like good sugar.
The macro I have is:
(define-syntax using-poly-math
(λ(stx)
(syntax-case stx ()
((_ exp exps ...)
(with-syntax ((+ (datum->syntax #'exp '+))
(- (datum->syntax #'exp '-))
(* (datum->syntax #'exp '*))
(expt (datum->syntax #'exp 'expt)))
#'(let ((+ poly-add)
(- poly-sub)
(* poly-times)
(expt poly-expt))
(begin exp
exps ...)))))))
My understanding of macros which capture variables is poor, compounded
by my also poor understanding of syntax-case, and in fact this was
kind of ripped from a blog post (I believe Eli's). But with it:
>* (let ((p1 '(1 1)))
* (using-poly-math
(+ p1 (expt p1 5))))
'(1 5 10 10 6 2)
Which is nice and concise.
I have two questions:
1) Is this kind of capturing macro a bad style?
2) Is this macro correct for what I'm trying to do? Is it expressed poorly?
Thanks for any insight,
Deren