A demo of continuation-pass-style (CPS) by finding the n-th number of fibonacci series with R5RS Scheme.

cps.scm

;; a demo of continuation-pass-style by finding the n-th number of fibonacci series.
;; works in R5RS scheme

(define +&
  (lambda (a b y)
      (y (+ a b)
)))

(define <&
  (lambda (a b y)
      (y (< a b)
)))

(define =&
  (lambda (a b y)
      (y (= a b)
)))

(define (fib& n y)
(<& n 2 (lambda (nlt2)
          (if nlt2
             (y 1)
             (fib-iter& n 2 1 1 y)
))))

(define (fib-iter& n i fib_n-1 fib_n-2 y)
  (+& fib_n-1 fib_n-2 (lambda (fib-n)
                        (let
                            ((fib_n fib-n))
                            (=& n i (lambda (neqi)
                                      (if neqi
                                         (y fib_n)
                                         (+& i 1 (lambda (i+1)
                                                   (fib-iter& n i+1 fib_n fib_n-1 y)
)))))))))

(fib& 1 (lambda(x) x))
(fib& 10 (lambda(x) x))