Re: lazy-let & loop

> *  <[email protected]> [2017-12-20 18:16:08 +0000]:
>
> 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.

This is a proof of concept.

If we can fix all the LOOP bugs (search for #-CLISP in loop.tst) using
lazy-let, it would lend support to my TAGLET proposal:

(taglet (vars) &body) == (lazy-let (vars) (tagbody ,@body))

TAGLET fits the way LOOP is generally _perceived_ very well.

> Actually, it has huge costs in clisp - try out DISASSEMBLE - as the
> closures are not inlined.

Inlining the flet closures has been in clisp man page TODO section as
long as I can remember. ;-)

Thanks.

-- 
Sam Steingold (http://sds.podval.org/) on darwin Ns 10.3.1504
http://steingoldpsychology.com http://www.childpsy.net https://jihadwatch.org
http://mideasttruth.com http://americancensorship.org http://memri.org
When told to go to hell, ask for directions.

------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
_______________________________________________
clisp-devel mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/clisp-devel