Nested arrays and operators

Abstract

Following the new direction taken by the ISO Standards Committee meeting in Palo Alto, during August, 1991, an extended APL standard is considered using a nested array basis with particular features from IBM's APL2 program product. APL2 develops from ISO APL with the relaxation of two early scalar constraints. Enclose, disclose, and each are derived from properties of bracket indexing and scalar conformance. Identities connect these new operations with the structural operators. Decisions must be made on what features from other systems, presently implemented or not, should be added to the nested array foundation. Candidates for inclusion are rank and depth operators and various sorts of program definable data types. Comparisons are made between constructs, and tentative conclusions are advanced.