(repl-substring string target repl pos)
Replaces target with repl in string at pos.
Norman Walsh, <ndw@nwalsh.com>
(define (repl-substring string target repl pos) ;; Replace substring in a string (let ((matches (repl-substring? string target pos))) (if matches (string-append (substring string 0 pos) repl (substring string (+ pos (string-length target)) (string-length string))) string)))