Casl Semantics

Abstract

This part of the Casl Reference Manual defines the formal semantics of the language Casl, as informally presented in the Casl Summary (Part I). Apart from this Introduction, which is partly devoted to defining some basic notation and explaining the style of the semantics, the structure of this document is deliberately almost identical to the structure of the Casl Summary to aid cross-reference. As in the Casl Summary, Chap. 2 deals with many-sorted basic specifications, and Chap. 3 extends this by adding features for subsorted basic specifications. Chapter 4 provides structured specifications, together with specification definitions, instantiations, and views. Chapter 5 summarizes architectural and unit specifications, which, in contrast to structured specifications, prescribe the separate development of composable, reusable implementation units. Finally, Chap. 6 considers specification libraries. There are two exceptions to the structural match between this document and the Casl Summary. One is in Chap. 4, where the subsections of Sect. 4.1 define many concepts and notations underlying the semantics of structured specifications that were not mentioned in the Casl Summary. The other is in Chap. 5, where Sect. 5.6 presents a more precise analysis of the constructs considered in Sects. 5.2–5.5.