Re: lazy-let & loop

[<Joe...@t-...>]

Hi again,

Having fun, here's the version with the need for most gensyms removed:

(defmacro lazy-let1 ((var) &body body)
  (let ((shadow (gensym (symbol-name var))))
    `(let ((,shadow 'unbound))
       (flet ((,shadow () (if (eq ,shadow 'unbound) ,var ,shadow))
	      ((setf ,shadow) (,var) (setf ,shadow ,var)))
	 (symbol-macrolet ((,var (,shadow))) .,body)))))

(setf ,shadow) is indeed defined as (setf ,shadow) - scoping rules!

'unbound should be replaced by the usual unique CONS trick, and perhaps #1#...

This is just for the fun, I don't like this macro because of the run-time check.
Actually, it has huge costs in clisp - try out DISASSEMBLE - as the closures are not inlined.

Regards,
	Jörg