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Paste # 65202
2017-02-23 05:24:55

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Embed:

#lang racket
(define (my-replace L n c)
  (let loop ((x 1)
             (ol '()))
    (cond
      [(> x (length L))
       (reverse ol)]
      [(= x n)
       (loop (add1 x) (cons c ol))]
      [else
       (loop (add1 x) (cons (list-ref L (sub1 x)) ol))])))

(my-replace "(a b c d e) 3 "a")

=>

prog:13:29: read: expected a closing '"'
  context...:
   /home/pasterack/racket66/collects/syntax/module-reader.rkt:185:17: body
   /home/pasterack/racket66/collects/syntax/module-reader.rkt:182:2: wrap-internal
   /home/pasterack/racket66/collects/racket/../syntax/module-reader.rkt:64:9: lang:read-syntax
   /home/pasterack/racket66/share/pkgs/scribble-lib/scribble/private/manual-code.rkt:112:0: get-tokens
   /home/pasterack/racket66/share/pkgs/scribble-lib/scribble/private/manual-code.rkt:56:0: typeset-code15
   /home/pasterack/pasterack/tmp/65202/65202code.scrbl: [running body]
   ...cket/cmdline.rkt:179:51
   /home/pasterack/racket66/share/pkgs/scribble-lib/scribble/run.rkt: [running body]