Axioms for user‐defined operators
Ian C. Pyle · Software Practice and Experience · 1980
Abstract Some programming languages allow the programmer to define operators. Algol‐68 allows user‐defined operator symbols with user‐defined priorities and user‐defined bodies; nevertheless the language rules insist on left‐to‐right evaluation of equal precedence operators. The new Department of Defense DoD language Ada allows the programmer to define new operators, but restricts them to language‐defined operator symbols with language‐defined priorities: in other words, only user‐defined bodies. The language rules concerning operators are therefore stronger, and imply properties of operators: ‘axioms’, which should apply even for use‐rdefined bodies. The paper discusses sensible constraints which should be accepted for user‐defined operators An earlier version of this paper was presented at the IFIPWG2.4 (System Implementation Languages) meeting at Twente, June 1978. The author thanks members of WG2.4 for their comments. .