The list set generator
Stuart C. Shapiro · Communications of the ACM · 1970
The list set generator is defined and algorithms for its use are given.The list set generator is a construct which may be added to a list processing system or any system that handles sets.It efficiently generates the set which results from any expression involving sets and set operators.The efficiency derives from evaluating the expression as a whole and in parallel, rather than evaluating subexpressions and then using those sets to arrive at the final result.