random ( obj -- elt )
Generating random integers

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random-32 ( -- n )

Vocabulary
random

Inputs

obj

an object

Outputs

elt	a random element

Word description
Outputs a random element of the input object, or outputs f if the object contains no elements.

Examples

USING: random prettyprint ; 10 random .
3

USING: random prettyprint ; SYMBOL: heads SYMBOL: tails { heads tails } random .
heads

Definition

IN: random

GENERIC: random ( obj -- elt )

Methods

USING: assocs random ;

M: assoc random >alist random ;


USING: kernel math random ;

M: float random
    [ f ] [ 0.0 swap uniform-random-float ] if-zero ;


USING: accessors hash-sets hashtables.private kernel math random
sequences.private sets ;

M: hash-set random
    dup cardinality
    [ drop f ] [
        [ 0 ] [ array>> ] [ random ] tri* 1 +
        [ [ 2dup array-nth tombstone? [ 1 + ] 2dip ] loop ]
        times [ 1 - ] dip array-nth
    ] if-zero ;


USING: accessors arrays assocs hashtables hashtables.private
kernel math random sequences.private ;

M: hashtable random
    dup assoc-size
    [ drop f ] [
        [ 0 ] [ array>> ] [ random ] tri* 1 +
        [ [ 2dup array-nth tombstone? [ 2 + ] 2dip ] loop ]
        times [ 2 - ] dip
        [ array-nth ] [ [ 1 + ] dip array-nth ] 2bi 2array
    ] if-zero ;


USING: math random random.private ;

M: integer random [ f ] [ random-integer ] if-zero ;


USING: kernel random random.private sequences ;

M: sequence random
    [ f ] [ [ length random-integer ] keep nth ] if-empty ;


USING: random sets ;

M: set random members random ;