Common Lisp the Language 2nd Edition

26. Loop

PREFACE: X3J13 voted in January 1989 (LOOP-FACILITY)   to adopt an extended definition of the loop macro as a part of the forthcoming draft Common Lisp standard.

This chapter presents the bulk of the Common Lisp Loop Facility proposal written by Jon L White. I have edited it only very lightly to conform to the overall style of this book and have inserted a small number of bracketed remarks identified by the initials GLS. (See the Acknowledgments to this second edition for acknowledgments to others who contributed to the Loop Facility proposal.)

- Guy L. Steele Jr.

• Introduction
• How the Loop Facility Works
• Parsing Loop Clauses
  • Order of Execution
  • Kinds of Loop Clauses
  • Loop Syntax
• User Extensibility
• Loop Constructs
• Iteration Control
• End-Test Control
• Value Accumulation
• Variable Initializations
• Conditional Execution
• Unconditional Execution
• Miscellaneous Features
  • Data Types
  • Destructuring