amb time

(define (range low high) (if (> low high) (amb) (amb low (range (add1 low) high))))
'range
cpu time: 0 real time: 0 gc time: 0
(range 1 10)
1
2
3
4
5
6
7
8
9
10
cpu time: 3 real time: 3 gc time: 0
(let ([x (range 1 10)]) (if (> x 5) (amb) x))
1
2
3
4
5
cpu time: 2 real time: 2 gc time: 0