union-all ( sets -- set/f )
Factor handbook » The language » Collections » Sets » Operations on sets

Prev:	set= ( set1 set2 -- ? )
Next:	intersect-all ( sets -- set/f )

Vocabulary
sets

Inputs

sets	a sequence of sets

Outputs

set/f

a set or f

Word description
Outputs the union of a sequence of sets, or f if the sequence is empty.

Definition

USING: kernel sequences sets.private ;

IN: sets

: union-all ( sets -- set/f )
    [ f ] [ [ [ ?members ] map concat ] [ first ] bi set-like ]
    if-empty ;