Apparently some implementations have tail-recursion modulo cons. You spot a tail-recursive function where the result is placed in the cdr, and you compile your

Apparently some implementations have tail-recursion modulo cons. You spot a tail-recursive function where the result is placed in the cdr, and you compile your code so that it chains cells by calling "set-cdr!" For example (using CL), the code could be turned into two auxiliary map%% and map% functions (map% would be what a call to map expands into). (defun map%% (cons function list) (declare (optimize (speed 3) (debug 1) (safety 1)) (type function function) (type list list) (type cons cons)) (when list (map%% (setf (cdr cons) (list (funcall function (first list)))) function (rest list)))) (defun map% (function list) (let ((fresh (cons nil nil))) (map%% fresh function list) (rest fresh))) Testing TCO: (map% #'1+ '#1=(5 6 8 4 5 1 3 . #1#)) Heap exhausted, game over.