Добре дошли в DrRacket, версия 7.1 [3m].
Език: R5RS [потребителски]; memory limit: 128 MB.
> (define undefined (delay (+ a 3)))
> (force undefined)
[image] [image] a: undefined;
 cannot reference an identifier before its definition
> (force undefined)
[image] [image] a: undefined;
 cannot reference an identifier before its definition
> (define a 5)
> (force undefined)
8
> (force undefined)
8
> (define undefined2 (lambda () (+ b 3)))
> (undefined2)
[image] [image] b: undefined;
 cannot reference an identifier before its definition
> (define b 10)
> (undefined2)
13
> (fact 10000)
28462596809170545.....
> (* 0 (fact 10000))
0
> (* 0 (fact 15000))
0
> (* 0 (fact 20000))
0
> (define bigpromise (* 0 (fact 20000)))
> (define bigpromise (delay (* 0 (fact 20000))))
> (define bigpromise (delay (* 0 (fact 20000))))
> (force bigpromise)
0
> (force bigpromise)
0
> (force bigpromise)
0
> (define bigpromise2 (lambda () (* 0 (fact 20000))))
> (bigpromise2)
0
> (bigpromise2)
0
> (force undefined)
[image] [image] undefined: undefined;
 cannot reference an identifier before its definition
> (define undefined (delay (+ a 2)))
> (force undefined)
[image] [image] a: undefined;
 cannot reference an identifier before its definition
> (define a 3)
> (force undefined)
5
> (define a 10)
> (force undefined)
5
> (set! a 15)
> (force undefined)
5
> (define s (cons-stream 1 (cons-stream (* 0 (fact 20000)) the-empty-stream)))
> (tail s)
(0 . #<promise>)
> s
(1 . #<promise>)
> (tail s)
(0 . #<promise>)
> (define promise (mydelay (+ a 3)))
> promise
#<procedure:promise>
> (myforce promise)
[image] [image] a: undefined;
 cannot reference an identifier before its definition
> (define a 45)
> (myforce promise)
48
> (define s (cons-stream 1 (cons-stream (* 0 (fact 20000)) the-empty-stream)))
> s
(1 . #<promise>)
> (tail s)
(0 . #<promise>)
> (tail s)
(0 . #<promise>)
> (define s (enum 1 10000000000000000000000000000000000000000))
> s
(1 . #<promise>)
> (tail s)
(2 . #<promise>)
> (tail (tail s))
(3 . #<promise>)
> (take 10 (enum 1 1000000000000000000000))
(1 2 3 4 5 6 7 8 9 10)
> (take 10 (enum 1 5))
[image] [image] mcar: contract violation
  expected: mpair?
  given: ()
> (take 10 (enum 1 5))
(1 2 3 4 5)
> (search-stream even? (enum 1 10))
(2 . #<promise>)
> (search-stream even? (enum 1 10))
(2 . #<promise>)
> (search-stream negative? (enum 1 10))
#f
> (take 10 (from 20))
(20 21 22 23 24 25 26 27 28 29)
> (take 20 fibs)
(0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181)
> (define (1+ n) (+ n 1))
> (take 10 (map-stream 1+ nats))
(1 2 3 4 5 6 7 8 9 10)
> (take 10 (map-stream 1+ fibs))
(1 2 2 3 4 6 9 14 22 35)
> (take 10 evens)
(0 2 4 6 8 10 12 14 16 18)
> (take 10 (zip-stream + nats nats))
[image] [image] zip-stream: undefined;
 cannot reference an identifier before its definition
> (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)
> (take 10 (zip-streams - nats nats))
(0 0 0 0 0 0 0 0 0 0)
> (take 10 (map-stream + nats nats))
(0 2 4 6 8 10 12 14 16 18)
> (take 10 (map-stream + nats nats nats))
(0 3 6 9 12 15 18 21 24 27)
> 
(take 10 (map-stream + nats nats nats fibs nats))
(0 5 9 14 19 25 32 41 53 70)
> 
(take 10 (map-stream exp nats))
(1
 2.718281828459045
 7.38905609893065
 20.085536923187668
 54.598150033144236
 148.4131591025766
 403.4287934927351
 1096.6331584284585
 2980.9579870417283
 8103.083927575384)
> (tail 10 (map-stream +))
[image] [image] tail: arity mismatch;
 the expected number of arguments does not match the given number
  expected: 1
  given: 2
  arguments> (take 10 ones)
(1 1 1 1 1 1 1 1 1 1)
> (map-stream + ones nats)
(1 . #<promise>)
> (take 10 (map-stream + ones nats))
(1 2 3 4 5 6 7 8 9 10)
> (take 10 nats)
(0 1 2 3 4 5 6 7 8 9)
> (take 10 fibs)
(0 1 1 2 3 5 8 13 21 34)
> (take 10 (filter-stream (notdivides 2) nats))
(1 3 5 7 9 11 13 15 17 19)
> (take 10 (filter-stream (notdivides 3) nats))
(1 2 4 5 7 8 10 11 13 14)
> (take 10 (filter-stream (notdivides 5) nats))
(1 2 3 4 6 7 8 9 11 12)
> (take 10 (sieve (from 2)))
(2 3 5 7 9 11 13 15 17 19)
> (take 10 (sieve (from 2)))
(2 3 5 7 11 13 17 19 23 29)
> (take 100 (sieve (from 2)))
> (take 20 (sieve (from 2)))
(2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71)
> primes
(2 . #<promise>)
> (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 (sieve2 (from 2)))
(2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71)