Syntactic control of interference Part 2

Abstract

In 1978, we proposed that Algol-like languages should be constrained so that aliasing between variables and, more generally, interference between commands or procedures would be syntactically detectable in a fail-safe manner. In particular, we proposed syntactic restrictions that prohibited interference between distinct identifiers, while permitting interference between qualifications of the same identifier. However, these restrictions had the unfortunate property that syntactic correctness was not preserved by beta reduction.

In the present paper, we show how this difficulty can be avoided by the use of a variant of conjunctive types. We also give an algorithm for typechecking explicitly typed programs.

Research supported by NSF Grant CCR-8620191. A portion of the research was also sponsored by the Defense Advanced Research Projects Agency (DOD), ARPA Order No. 4976, under contract number F33615-87-C-1499, monitored by the Air Force Wright Aeronautical Laboratories, Wright-Patterson AFB, Ohio. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of any agency of the US Government.