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Stray Birds

I have not seen anything here of late and my work machine is down, so...
------------------------------------------------------------------------

At some point it would be nice to use multiple value bindings so that local
scopes may export definitions in a more declarative style.  I.e. the set!'s
really bother me in:

(define foo 'bogus)
(define bar 'bogus)
(let ()
  ...  ;; local shared bindings
  (set! foo internal-foo)
  (set! bar (lambda (..) ...)
)

So I would like to propose 2 special forms: LET-VALUES and DEFINE-VALUES. 
Let-values is trivial with HL macros, but define-values is not.

;================
; PROPOSED FORMS: let-values and define-values
;================

;; <values-form> must end in a VALUES form which has the same number of
values as 
;; there are names in <name>... .

;; Bind names to values in body
;;
;;(let-values ( (<name>...) <values-form> )  
;;    <body-form>...)


;; Define multiple names to have values
;;
;;(define-values (<name>...)
;;    <body-form>...
;;    <values-form>)


;======================
; CHEAP IMPLEMENTATION
;======================

(define-syntax LET-VALUES
    (syntax-rules ()
        ((let-values ( (<name> ...) <values-form>) <body> ...)
        ; =>
         (call-with-values 
                 (lambda () <values-form>)
                 (lambda (<name> ...) <body> ...))
)    )    )

;; This next can't be done in HL macros because of the <value>s, but you get
;; the idea.
(define-syntax DEFINE-VALUES
    (syntax-rules ()
        ((define-values (<name> ...) <body> ...)
        ; =>
         (begin
             (define <name> #f) ...
             (call-with-values
                     (lambda () <body> ...)
                     (lambda (<value> ...) (set! <name> <value>) ...))  ;; 8^(
         ))
)    )


;; QUESTIONS:

- Since there HL implementations which don't include low-level facilities,
can we still simply put define-values in the implementors-can-ignore
library? 
- Are the names ok? {e.g. values-define, multiple-values-define,
with-values, ...}
- Other suggestions?

How about using WITH or BIND for named let?  {Boy, this should start some
mail! 8^}

-Ken                              kend@newton.apple.com