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Re: [srfi-11] LET-VALUES wrapup (was: Re: Another vote for more parens)



lth = Lars Thomas Hansen <lth@xxxxxxxxxxx>
eh = erik hilsdale <ehilsdal@xxxxxxxxxxxxxx>

  eh>   (let-values ((IDENTIFIER EXP)) BODY) 
  eh>   ==> (let ((IDENTIFIER EXP)) BODY)
  eh>          or, equivalently
  eh>       (call-with-values (lambda () EXP) (lambda (IDENTIFIER) BODY))

  lth> Holy cow, absolutely not!

  lth> 	 (let-values ((I E)) BODY)
  lth> 	 ==>  (call-with-values (lambda () E) (lambda I BODY))

  lth> There is only one case: any <formals> is allowable, and does
  lth> exactly what you would expect.  I thought I was clear about
  lth> this but I guess I must not have been.  The proposed expansion
  lth> above is in any case not allowed by the Report.

  lth> There is nothing profound about my spec for LET-VALUES.  It is
  lth> merely sugar that aims to improve readability of programs (by
  lth> removing the use of CPS introduced by CALL-WITH-VALUES).  Among
  lth> other things I want to be able to capture all the returned
  lth> values in a list.  Mike (and maybe Dave, I can't tell) wants to
  lth> perserve the equivalence of (values 1) and 1 when
  lth> destructuring; I don't mind that, but it competes with the
  lth> ability to capture all values, which I value much more highly.

Sorry for the misunderstanding (or, really, the misattribution).  I
was summarizing what Mike-and-maybe-Dave (*smile*) seemed to be aiming
for.  As I poorly communicated in the rest of the message, I'm all for
the non-profound LET-VALUES. 

	(let-values ((FORMALS EXP) ...) BODY)

-erik