The SL5 procedure mechanism

ABSTRACT

This paper describes an integrated procedure mechanism that permits procedures to be used as recursive functions or as coroutines. This integration is accomplished by treating procedures and their activation records (called environments) as data objects and by decomposing procedure invocation into three separate components at the source-language level. In addition, argument binding is under the control of the programmer, permitting the definition of various methods of argument transmission in the source language itself. The resulting procedure mechanism, which is part of the SL5 programming language, is well suited to goal-oriented problems and to other problems that are more readily programmed by using coroutines. Several examples are given.

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INDEX TERMS

Primary Classification:
  D. Software
  D.3 PROGRAMMING LANGUAGES
      D.3.3 Language Constructs and Features
          Subjects: Procedures, functions, and subroutines

Additional Classification:
  D. Software
  D.3 PROGRAMMING LANGUAGES
      D.3.4 Processors
          Subjects: Interpreters

  I. Computing Methodologies
  I.2 ARTIFICIAL INTELLIGENCE
      I.2.8 Problem Solving, Control Methods, and Search
          Subjects: Backtracking

General Terms:
Design, Languages, Performance, Theory

Keywords:
SNOBOL4, backtracking, coroutines, interpreters, procedures, programming languages