bharath1097/tco.el

Tail call recursion in Emacs lisp

tco.el

Tail call optimisation for Emacs lisp

Example usage:

(require 'tco)

(defun-tco fact (x &optional accum)
  (setq accum (or accum 1))
  (if (eql x 1) accum
    (fact (1- x) (* accum x))))

;; values greater than `max-lisp-eval-depth'
;; would cause stack overflow here:
(fact 700)

Todo

• Better example than factorial, since 32-bit Emacs overflows so 32! is 0.
• Unit tests