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use for/list intead of a (one off) map/i function.

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This commit is contained in:
Robby Findler 2010-12-06 09:19:53 -06:00
parent 45a97cb561
commit b884623da2
1 changed files with 4 additions and 10 deletions
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14
collects/2htdp/private/img-err.rkt
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@ -49,8 +49,10 @@
(with-syntax ([(i ...) (build-list len add1)]) (with-syntax ([(i ...) (build-list len add1)])
#`(define (fn-name args ... . final-arg) #`(define (fn-name args ... . final-arg)
(let ([args (check/normalize 'fn-name 'args args i)] ... (let ([args (check/normalize 'fn-name 'args args i)] ...
[final-arg (map/i (λ (x j) (check/normalize 'fn-name 'final-arg x (+ #,(+ len 1) j))) [final-arg
final-arg)]) (for/list ([x (in-list final-arg)]
[j (in-naturals #,(+ len 1))])
(check/normalize 'fn-name 'final-arg x j))])
body ...))))] body ...))))]
[(define/chk (fn-name args ...) body ...) [(define/chk (fn-name args ...) body ...)
(with-syntax ([(i ...) (build-list (length (syntax->list #'(args ...))) add1)] (with-syntax ([(i ...) (build-list (length (syntax->list #'(args ...))) add1)]
@ -70,14 +72,6 @@
(let ([arg-ids (check/normalize 'fn-name 'arg-ids arg-ids i)] ...) (let ([arg-ids (check/normalize 'fn-name 'arg-ids arg-ids i)] ...)
body ...)))]))) body ...)))])))
(define (map/i f l)
(let loop ([l l]
[i 0])
(cond
[(null? l) null]
[else (cons (f (car l) i)
(loop (cdr l) (+ i 1)))])))
;; check/normalize : symbol symbol any number -> any ;; check/normalize : symbol symbol any number -> any
;; based on the name of the argument, checks to see if the input ;; based on the name of the argument, checks to see if the input
;; is valid and, if so, transforms it to a specific kind of value ;; is valid and, if so, transforms it to a specific kind of value