c.rkt

#lang racket/base

(define M 100)
(define N 1000000)

;; Baseline tail-call loop
(time
 (let loop ([j 0])
   (cond
    [(= j N) 'done]
    [else
     (let loop ([i 0])
       (cond
        [(= i M) 'done]
        [else (loop (add1 i))]))
     (loop (add1 j))])))

;; WCM around tail call
(time
 (let loop ([j 0])
   (cond
    [(= j N) 'done]
    [else
     (let loop ([i 0])
       (cond
        [(= i M) 'done]
        [else (with-continuation-mark
                'k i
                (loop (add1 i)))]))
     (loop (add1 j))])))

;; ----------------------------------------


;; Baseline non-tail-call recursion
(time
 (let loop ([j 0])
   (cond
    [(= j N) 'done]
    [else
     (let loop ([i 0])
       (cond
        [(= i M) i]
        [else (sub1 (loop (add1 i)))]))
     (loop (add1 j))])))

;; WCM non-tail-call recursion
(time
 (let loop ([j 0])
   (cond
    [(= j N) 'done]
    [else
     (let loop ([i 0])
       (cond
        [(= i M) 0]
        [else (with-continuation-mark
                'k i
                (sub1 (loop (add1 i))))]))
     (loop (add1 j))])))