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; loopy loops

(define (range . args)
  (case (length args)
    ((1) (range 0 (car args) (if (negative? (car args)) -1 1)))
    ((2) (range (car args) (cadr args) (if (< (car args) (cadr args)) 1 -1)))
    ((3) (let ((le? (if (negative? (caddr args)) >= <=)))
           (let loop ((x(car args)) (xs '()))
             (if (le? (cadr args) x)
                 (reverse xs)
                 (loop (+ x (caddr args)) (cons x xs))))))
    (else (error 'range "unrecognized arguments"))))

(define (f n) (range 1 (+ n 1)))

(display (f 10)) (newline) (display "---") (newline)

(define (f n)
  (for-each (lambda (x) (display x) (newline)) (range 1 (+ n 1))))

(f 10) (display "---") (newline)

(define (f n)
  (and (< 1 n) (f (- n 1)))
    (display n) (newline))

(f 10) (display "---") (newline)

(define (f n)
  (let f ((n n) (i 1))
    (display i) (newline)
    (and (< 1 n) (f (- n 1) (+ i 1)))))

(display (f 10)) (newline) (display "---") (newline)

(define (f n)
  (define (g i)
    (display i) (newline)
    (and (< i n) (g (+ i 1))))
  (if (g 1) #f))

(f 10) (display "---") (newline)

(define (f n)
  (define (g n i)
    (let ((j (/ n)))
      (display i) (newline)
      (g (- n 1) (+ i 1))))
    (g n 1))

(f 10)

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