Algebraic semantics of exception handling

Abstract

In this paper, a new semantics for exception handling in algebraic specifications is provided. Our formalism allows all forms of exception and error handling (several error messages, implicit error propagation rule, exception recovery policy), while preserving the existence of initial models. It handles complex examples where various exceptional cases (leading to different processings) can be specified. The main concept of our approach is the distinction between exception and error. This formalism allows use of congruences in a similar manner as in the classical abstract data type theory. Moreover, we show how a functorial semantics of enrichment can be carried over to our framework, and we show how hierarchical consistency and sufficient completeness can be redefined. These results provide a firm basis for writing modular, structured specifications with exception handling features.