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copied!<p>You can certainly write something that takes in a quoted s-expression and outputs the translation as a quoted s-expression.</p> <p>Start with simply translating well-formed lists like <code>'(#\c #\a #\d #\r)</code> into your first/rest s-expressions.</p> <p>Now build the solution with symbol?, symbol->string, regexp-match #rx"^c(a|d)+r$", string->list, and map</p> <p>Traverse the input. If it is a symbol, check the regexp (return as-is if it fails), convert to list, and use your starting translator. Recurse on the nested expressions.</p> <p>EDIT: here's some badly written code that can translate source-to-source (assuming the purpose is to read the output)</p> <pre><code>;; translates a list of characters '(#\c #\a #\d #\r) ;; into first and rest equivalents ;; throw first of rst into call (define (translate-list lst rst) (cond [(null? lst) (raise #f)] [(eq? #\c (first lst)) (translate-list (rest lst) rst)] [(eq? #\r (first lst)) (first rst)] [(eq? #\a (first lst)) (cons 'first (cons (translate-list (rest lst) rst) '()))] [(eq? #\d (first lst)) (cons 'rest (cons (translate-list (rest lst) rst) '()))] [else (raise #f)])) ;; translate the symbol to first/rest if it matches c(a|d)+r ;; pass through otherwise (define (maybe-translate sym rst) (if (regexp-match #rx"^c(a|d)+r$" (symbol->string sym)) (translate-list (string->list (symbol->string sym)) rst) (cons sym rst))) ;; recursively first-restify a quoted s-expression (define (translate-expression exp) (cond [(null? exp) null] [(symbol? (first exp)) (maybe-translate (first exp) (translate-expression (rest exp)))] [(pair? (first exp)) (cons (translate-expression (first exp)) (translate-expression (rest exp)))] [else exp])) 'test-2 (define test-2 '(cadr (1 2 3))) (maybe-translate (first test-2) (rest test-2)) (translate-expression test-2) (translate-expression '(car (cdar (list (list 1 2) 3)))) (translate-expression '(translate-list '() '(a b c))) (translate-expression '(() (1 2))) </code></pre> <p>As mentioned in the comments, I am curious why you'd want a macro. If the purpose is to translate source into something readable, don't you want to capture the output to replace the original?</p>

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