*random-state* [Variable]

Value Type::

a random state.

Initial Value::

implementation-dependent.

Description::

The current random state, which is used, for example, by the function random when a random state is not explicitly supplied.

Examples::

 (random-state-p *random-state*) =>  true
 (setq snap-shot (make-random-state))
 ;; The series from any given point is random,
 ;; but if you backtrack to that point, you get the same series.
 (list (loop for i from 1 to 10 collect (random))
       (let ((*random-state* snap-shot))
         (loop for i from 1 to 10 collect (random)))
       (loop for i from 1 to 10 collect (random))
       (let ((*random-state* snap-shot))
         (loop for i from 1 to 10 collect (random))))
=>  ((19 16 44 19 96 15 76 96 13 61)
    (19 16 44 19 96 15 76 96 13 61)
    (16 67 0 43 70 79 58 5 63 50)
    (16 67 0 43 70 79 58 5 63 50))

Affected By::

The implementation.

random.

See Also::

section make-random-state [Function] , section random [Function] , random-state

Notes::

Binding *random-state* to a different random state object correctly saves and restores the old random state object.

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