How Haskell's infix $ operator might look in Scheme

dollar.scm

(define reduce
  (lambda (subject complete-rules rules generation-id)
    (if (null? rules)
      subject
      (let* ((rule-pair     (car rules))
             (rest-of-rules (cdr rules))
             (pattern       (car rule-pair))
             (replacements  (cdr rule-pair))
             (new-gen-id    (+ generation-id 1))
             (new-subject   (apply-rule subject pattern replacements generation-id)))
        (if new-subject
          (reduce new-subject complete-rules complete-rules new-gen-id)
          (reduce subject complete-rules rest-of-rules new-gen-id))))))

; ... BECOMES ...

(define reduce $
  lambda (subject complete-rules rules generation-id) $
    if (null? rules)
      subject $
      let* ((rule-pair     $ car rules)
            (rest-of-rules $ cdr rules)
            (pattern       $ car rule-pair)
            (replacements  $ cdr rule-pair)
            (new-gen-id    $ + generation-id 1)
            (new-subject   $ apply-rule subject pattern replacements generation-id)) $
        if new-subject
          (reduce new-subject complete-rules complete-rules new-gen-id) $
          reduce subject complete-rules rest-of-rules new-gen-id)