Power set: Difference between revisions

=={{header|Factor}}==

We use hash sets, denoted by <code>HS{ }</code> brackets, for our sets. <code>members</code> converts from a set to a sequence, and <code><hash-set></code> converts back.

: add ( set elt -- newset ) 1array <hash-set> union ;

: powerset ( set -- newset ) members { HS{ } } [ dupd [ add ] curry map append ] reduce <hash-set> ;</lang>