Data abstraction, controlled iteration, and communicating processes
ALFS T. BERZTISS · 1980
Iterators provide access to elements of an abstract structured object in some sequence. It is argued that parallel composition of iterators should be achieved implicitly by means of a generalized for loop rather than by use of mutually interacting coroutines. The generalized for loop employs controlled iteration, which is shown to be a powerful yet inexpensive construct. The generalized for loop is consistent with block structure, and, for program proof purposes, is much more tractable than an unrestricted loop. Concrete programming examples are used extensively.