(define factorial (make-primitive-recursive * 1))

(define (make-add-select predicate)
  (make-primitive-recursive
    (lambda (x y) (if (predicate x)
                      (+ x y)
                      y))
    0))

(define add-odd (make-add-select odd?))

(define add-odd-iterative (recursive->iterative add-odd))

(define fib (make-two-recursive 
              (lambda (x y z) (+ y z))
              0
              1))

(define fib-iterative (two-recursive->iterative fib))