Such an improvement would be very welcome (I don't like to have to split my lets because of one expression returning multiple values), and I vote for #2 (using square brackets makes it sufficiently readable IMO), unless someone spoils it all with an overseen big drawback... But I would be quite happy with "((values ID ...+) VAL-EXPR)" or even "(values (ID ...+) VAL-EXPR)" (although this one looks weird to me). Laurent <div class="gmail_quote">On Sun, Jun 3, 2012 at 8:40 PM, Neil Van Dyke <<a href="mailto:neil@neilvandyke.org" target="_blank">neil@neilvandyke.org</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> What do people think about this syntax addition for multiple values in "let" and "let*" (and perhaps "letrec")? I like using multiple-value returns, but two problems with using them with the "let"* family: 1. "let-values" and "let*-values" are long identifiers, and increase rightward drift, sometimes making the difference between a line break needed before right-hand-side (RHS) or not (which line break is ugly in a "let"* form). 2. If I have an existing "let"* that's not a *"-values" that already has a few clauses in it, and I want to add a multiple-value LHS to it, I have to go to the trouble of converting it to a "-values", which requires editing each clause to add parentheses. So, I've been wondering what would be a good way to support multiple values on a per-clause basis. Options I see: 1. Change "(ID VAL-EXPR)" to "(ID ...+ VAL-EXPR)". I am shying away from this one because it seems error-prone, and the standard indenter won't know a good way to break such a clause across multiple lines, but it does have some appeal. 2. In addition to "(ID VAL-EXPR)", have "((ID ...+) VAL-EXPR)". This could work. One drawback I see is if in the future someone wants to have some funky generalized-"set!" selectors that have a parenthesized form, and have those work with the "let"* forms. I'm not currently interested in such "set!" selectors. Another small drawback is that we'll sometimes see "(let (((ID" three parentheses sometimes, like we do with "let-values", which is not the most visually pleasant thing to see. 3. In addition to "(ID VAL-EXPR)", have "((values ID ...+) VAL-EXPR)". This avoids the hypothetical problem with some future "set!" selectors, since I doubt is going to use "values" for the name of such a selector with any other purpose. This still has the three-parentheses problem like option #2. 4. In addition to "(ID VAL-EXPR)", have "(values ID ...+ VAL-EXPR)" or "(values (ID ...+) VAL-EXPR)". This avoids the three-parens of #2 and #3, it's not ambiguous with "values" used as a variable name, but it doesn't seem very Scheme-y, it has similar indent problem to option #1, and we still have rightward drift because of the "values" keyword. I lean a little towards option #2, but I think #1 or #3 would still be an improvement. #4 seems less-Schemely syntax, so I am reluctant to go there. For each option, the transform to Racket's canonical "let-values" is trivial. I don't know whether there are implications for TR syntax. A separate question -- which I don't care about, but someone else might -- is whether there should be ``rest'' ID in the LHS that gets a list of any remaining values from the RHS. I think this came up in a SRFI discussion a long time ago. I almost never have occasion to use such a feature, and it could complicate the syntax and the Racket compiler, so I'm not interested in a ``rest'' in the LHS. Neil V. ____________________ Racket Users list: <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/users</a> </blockquote></div>