http://akkartik.name/blog/2010-03-02-01-45-31-soc

gistfile1.txt

(require (lib "mzlib/pregexp"))

; Repeatedly run regexp-replace over a list of words.
(let ((words (call-with-input-file "ztmp.words2"
                                   (lambda(f) (read f)))))
  (letrec ((fn (lambda()
                  (print "iter") (newline)
                  (map (lambda(x) (regexp-replace (pregexp "b.*") x ""))
                       ; You can replace b with any letter. The input doesn't
                       ; even have any b's.
                       words)
                  (fn))))
    (fn)))