[racket] eginner's question on elementary textual replacement...

First of all, sounds like you have a substandard C compiler, and that 
you must be targeting a 4-bit microcontroller. :)

Regarding these micro-optimizations in Racket: if you are fairly new to 
Racket (I don't know), my suggestion is to avoid trying to optimize 
every word of allocation and every variable reference overhead, and 
instead focus on learning the idiomatic language.  I suggest pretending 
that variable references are negligible for now, and instead focus on 
things like trying to make tail calls, and trying to avoid variable 
mutations.

-- 
http://www.neilvandyke.org/