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relax contract for (random min max [rand-gen]) (#1626)

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Relax contract for `(random min max [rand-gen])` to accept any pair of
integers such that:
- `(< min max)`
- `(- max min)` is between 1 and 4294967087
This commit is contained in:
Benjamin Greenman 2017-03-06 18:43:04 -05:00 committed by GitHub
parent dbddb3785e
commit d8b78e823e
3 changed files with 56 additions and 30 deletions
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4
pkgs/racket-doc/scribblings/reference/numbers.scrbl
View File

@ -842,8 +842,8 @@ both in binary and as integers.
[rand-gen pseudo-random-generator?
(current-pseudo-random-generator)])
exact-nonnegative-integer?]
[(random [min (integer-in 1 4294967087)]
[max (integer-in 1 4294967087)]
[(random [min exact-integer?]
[max (integer-in (+ 1 min) (+ 4294967087 min))]
[rand-gen pseudo-random-generator?
(current-pseudo-random-generator)])
exact-nonnegative-integer?]

14
pkgs/racket-test-core/tests/racket/number.rktl
View File

@ -2462,9 +2462,15 @@
(test (begin (random-seed 23) (list (random 10) (random 20) (random 30)))
'random-seed-same
(begin (random-seed 23) (list (random 10) (random 20) (random 30))))
(test (begin (random-seed 23) (list (random 10 20) (random 20 30) (random 30 40)))
(test (begin (random-seed 23) (list (random 10 20) (random 20 30) (random 30 40)
(random 0 5) (random -10 10) (random -9 -3)
(random big-num (+ 10 big-num))
(random (- -3 big-num) (- big-num))))
'random-seed-same2
(begin (random-seed 23) (list (random 10 20) (random 20 30) (random 30 40))))
(begin (random-seed 23) (list (random 10 20) (random 20 30) (random 30 40)
(random 0 5) (random -10 10) (random -9 -3)
(random big-num (+ 10 big-num))
(random (- -3 big-num) (- big-num)))))
(test (begin (random-seed 23) (list (random-ref '(1 2 3)) (random-ref '(4 5 6)) (random-ref '(7 8 9))))
'random-seed-same3
(begin (random-seed 23) (list (random-ref '#(1 2 3)) (random-ref '#(4 5 6)) (random-ref '#(7 8 9)))))
@ -2484,7 +2490,11 @@
(err/rt-test (random 4294967088))
(err/rt-test (random (expt 2 32)))
(err/rt-test (random big-num))
(err/rt-test (random big-num))
(err/rt-test (random 10 5))
(err/rt-test (random -2 -3))
(err/rt-test (random 0 big-num))
(err/rt-test (random -big-num 0))
(random-seed 101)
(define x (list (random 10) (random 20) (random 30)))

68
racket/collects/racket/private/pre-base.rkt
View File

@ -98,18 +98,6 @@
(define-values (double-flonum?) ; for symmetry with single-flonum?
(lambda (x) (flonum? x)))
(define-values (enforce-random-int-range)
(lambda (x)
(unless (and (exact-positive-integer? x)
(<= x 4294967087))
(raise-argument-error 'random "(integer-in 1 4294967087)" x))))
(define-values (enforce-greater)
(lambda (x y)
(unless (> y x)
(raise-argument-error
'random
(string-append "integer greater than " (number->string x))
y))))
(begin-encourage-inline
(define-values (-random) ; more featureful than #%kernel's `random`
(let ([random ; to get the right name
@ -121,26 +109,54 @@
(random x)]
[(x y)
;; two args, either max and prng, or min and max
(cond [(exact-positive-integer? y) ; min and max case
(enforce-random-int-range x)
(enforce-random-int-range y)
(enforce-greater x y)
(+ x (random (- y x)))]
(cond [(exact-integer? y) ; min and max case
(unless (exact-integer? x)
(raise-argument-error 'random "exact-integer?" 0 x y))
(unless (< x y)
(raise-argument-error
'random
(string-append "(>/c " (number->string x) ")")
1 x y))
(let ([d (- y x)])
(unless (<= d 4294967087)
(raise-arguments-error
'random
"difference between arguments is greater than 4294967087"
"min" x "max" y))
(+ x (random d)))]
[(pseudo-random-generator? y) ; int and prng case
(enforce-random-int-range x)
(unless (and (exact-integer? x)
(<= 1 x 4294967087))
(raise-argument-error
'random "(integer-in 1 4294967087)" 0 x y))
(random x y)]
[else
(unless (exact-integer? x)
(raise-argument-error 'random "exact-integer?" 0 x y))
(raise-argument-error
'random
"(or/c (integer-in 1 4294967087) pseudo-random-generator?)"
y)])]
"(or/c exact-integer? pseudo-random-generator?)"
1 x y)])]
[(min max prng) ; three args: min, max, and prng
(enforce-random-int-range min)
(enforce-random-int-range max)
(enforce-greater min max)
(unless (pseudo-random-generator? prng)
(raise-argument-error 'random "pseudo-random-generator?" prng))
(+ min (random (- max min) prng))])])
(unless (exact-integer? min)
(raise-argument-error 'random "exact-integer?" 0 min max prng))
(unless (exact-integer? max)
(raise-argument-error 'random "exact-integer?" 1 min max prng))
(unless (< min max)
(raise-argument-error
'random
(string-append "(>/c " (number->string min) ")")
1 min max prng))
(let ([d (- max min)])
(unless (<= d 4294967087)
(raise-arguments-error
'random
"difference between first and second arguments is greater than 4294967087"
"min" min "max" max "rand-gen" prng))
(unless (pseudo-random-generator? prng)
(raise-argument-error
'random "pseudo-random-generator?" 2 min max prng))
(+ min (random d prng)))])])
random)))
(define-values (new:collection-path)