fib-binrec-a.sps

(import (rnrs) (ikarus))

(define (binrec f g h i j)
  (define (fun x)
    (if (f x)
        (g x)
        (j (fun (h x))
           (fun (i x)))))
  fun)

(define (constant x)
  (lambda (y)
    x))

(define (less-than= x)
  (lambda (y)
    (<= y x)))

(define (sub x)
  (lambda (y)
    (- y x)))

(define fib
  (binrec (less-than= 1)
          (constant 1)
          (sub 1)
          (sub 2)
          +))

(time (fib 34))