A case for while-until
Daniel P. Friedman, Stuart C. Shapiro · ACM SIGPLAN Notices · 1974
A new control structure construct, the while-until, is introduced as a syntactic combination of the while and the until. Examples are shown indicating that use of the while-until can lead to structured programs that are conceptually more manageable than those attainable without it. The while-until statement is then extended to a valuereturning expression which is shown to be more powerful than either the while or the until.