infinity.scm

; Turns out if your Scheme is lazy, you can do this:

(define (Y f)
  (f (Y f)))

; I'm not kidding, watch:

(define fact (Y (lambda (rec)
      (lambda (x)
        (if (= x 0)
            1
            (* x
               (rec (- x 1))))))))

(display (fact 6))
; =>  720