I'm trying use local-expand ( http://docs.racket-lang.org/reference/stxtrans.html?q=local-expand&q=local-expand#%28def._%28%28quote._~23~25kernel%29._local-expand%29%29 )
to partially expand sub-expressions. The only expressions I want to expand are known in advance, I'm just having trouble coming up with an elegant recursive algorithm for doing this. For example: (define (pred-a? x) (equal? x "hey")) (define (pred-b? y) (equal? y "there")) (define other-expr (lambda (z) (or (equal? z "you") (pred-a? z) (pred-b? z))) I'd like to expand other-expr like so that: (expand other-expr) >> (lambda (z) (or (equal? z "you") (equal? z "hey") (equal? z "there")) local-expand sort of works, but provides either too little expansion (#f stop-ids) whereby only the outer macro is expanded, or else it provides too much expansion (list of stop-ids), whereby "and" and "or" etc is expanded into let-values bindings. What I'd like is something in between. Rather than a "stop-list", I want an "include-list". I don't want or / and to expand to let-values, but I do want any of my special nested expressions (that might be 3 levels deep in an or clause) to expand inside the original or. I figure this is not possible using the built-in functions, and so set out trying to build a recursive function that would reconstruct the expression and selectively expand the inner procedures I wish by applying local-expand to the nested operands. My question is: 1.) Is there a simple library way to do this with local-expand that I'm missing? 2.) Does anyone have a hint or code example to do this manually using recursion? It should be simple enough but I'm embarrassed to admit how long I've wrestled with it. Thanks. -- Talk to you soon, Scott Klarenbach PointyHat Software Corp. www.pointyhat.ca p 604-568-4280 e sc...@pointyhat.ca 200-1575 W. Georgia Vancouver, BC V6G2V3 _______________________________________ To iterate is human; to recur, divine
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