> (from 10)
(10 . #<promise>)
> (take 10 (from 10))
(10 11 12 13 14 15 16 17 18 19)
> nats
(0 . #<promise>)
> 
> (take 20 fibs)
(0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181)
> (define facts (map-stream fact nats))
> facts
(1 . #<promise>)
> (take 10 facts)
(1 1 2 6 24 120 720 5040 40320 362880)
> (take 10 (map-stream (lambda (x) (* x x)) nats))
(0 1 4 9 16 25 36 49 64 81)
> (define evens (filter-stream even? nats))
> evens
(0 . #<promise>)
> (take 10 evens)
(0 2 4 6 8 10 12 14 16 18)
> (define negatives (filter-stream negative? nats))
[image] [image] user break
> (take 10 (zip-streams + nats fibs))
(0 2 3 5 7 10 14 20 29 43)
> (take 10 (zip-streams + nats nats))
(0 2 4 6 8 10 12 14 16 18)
> (take 10 (zip-streams * nats nats))
(0 1 4 9 16 25 36 49 64 81)
> (define x (+ x 1))
[image] [image] x: undefined;
 cannot reference an identifier before its definition
> (head ones)
1
> (head (tail ones))
1
> (take 10 ones)
(1 1 1 1 1 1 1 1 1 1)
> (take 10 (zip-streams + ones ones))
(2 2 2 2 2 2 2 2 2 2)
> (take 10 (zip-streams * ones ones))
(1 1 1 1 1 1 1 1 1 1)
> (take 10 (zip-streams + nats ones))
(1 2 3 4 5 6 7 8 9 10)
> (take 10 nats)
(0 1 2 3 4 5 6 7 8 9)
> (head (tail (tail nats)))
2
> (take 10 fibs)
(0 1 1 2 3 5 8 13 21 34)
> (take 20 fibs)
(0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181)
> (nondivisor 2)
#<procedure:.../scheme/streams.scm:64:23>
> (take 10 (filter-stream (nondivisor 2) nats))
(1 3 5 7 9 11 13 15 17 19)
> (take 10 (filter-stream odd? nats))
(1 3 5 7 9 11 13 15 17 19)
> (take 30 (filter-stream (nondivisor 5) nats))
(1 2 3 4 6 7 8 9 11 12 13 14 16 17 18 19 21 22 23 24 26 27 28 29 31 32 33 34 36 37)
> primes
(0 . #<promise>)
> (take 10 primes)
[image] [image] remainder: division by zero
> 
> (take 10 primes)
(2 3 5 7 9 11 13 15 17 19)
> (take 20 primes)
(2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71)
> (take 20 primes)
(2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71)