Re: SETF for functions returning multiple values.

Heh! This mirrors the discussion we just had.

I made my own digits become macro characters so that I can directly handle numbers written like these:

+1°23’.23
2026/06/08T11:10:09U+7
520-234-3474
and of course any number can be written with embedded comma or underscore:  1_234.5192_5542_112D0

I love it! Lisp no longer feels like a straightjacket to me. I can just directly type in the numbers as I need them. 

The only other time in my life where I had such freedom was in my ancient Forth Mount Control Systems on the world’s largest telescopes.

- DM


> On Jun 8, 2026, at 11:02, Tim Bradshaw (as tfb at tfeb dot org) <[email protected]> wrote:
> 
> (setf (values p1 p2) <form-returning-two-values>) should work when p1 and p2 are places (the spec talks about this).
> 
> If F is a function returning two values, then you can't write a (SETF F) function for it, but you can write a setf expansion pretty easily.  So then you just can say (setf (f ...) (values v1 v2)).
> 
> I don't think I've seen this done elsewhere.  Does it strike people as reasonable?
> 
> The reason I'm asking is that the delimited-string reading thing I've been cleaning up now lets you control the closing delimiter, so that for instance #D[foo/bar.ldat] might read as the contents of the file foo/bar.ldat (ie the opening and closing delimiters are different now, which they used not to be.
> 
> The function which lets you set up handlers is get-dsr-handler and it now returns two values the handler (or NIL) and the closing delimiter (or NIL if it's the same as the opening delimiter).
> 
> So I want to be able to say (setf (get-dsr-handler #\[) (values my-handler #\])) say.
> 
> --tim
> 
> [The actual hidden motivation for this is an utterly perverse usage I thought of: you can make any digit character be an opening delimiter and the closing delimiter for all of them be #\., and with a suitable handler function
> 
> ? #D1213,456,789.
> 1213456789
> 
> And even
> 
>> #16DFFFF FF00 ABCD.
> 281474959977421
> 
> So that's pretty neat.]
> 
> 
> 
> _______________________________________________
> Lisp Hug - the mailing list for LispWorks users
> [email protected]
> http://www.lispworks.com/support/lisp-hug.html


_______________________________________________
Lisp Hug - the mailing list for LispWorks users
[email protected]
http://www.lispworks.com/support/lisp-hug.html