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Re: what about dropping rest-lists?




I did a more systematic analysis of the requirements and the alternatives.
It turned out that the real problem is not the presence of the VALUES-
syntax, but the limits of the "just list the variables"-syntax.

As a logical conclusion I will stretch the "list the variables"-syntax to
include the "."-notation in the cases it can cover (except the "no values"
case due to syntactic robustness), and leave the VALUES-syntax in
for full generality and uniformity.

This design reduces the cases in which VALUES *must* be used to
a) no values at all and
b) a single variable receiving the list of all values.

...hopefully there will be a new version of the SRFI, soon.

Sebastian.

----
Dr. Sebastian Egner
Senior Scientist Channel Coding & Modulation
Philips Research Laboratories
Prof. Holstlaan 4 (WDC 1-051, 1st floor, room 51)
5656 AA Eindhoven
The Netherlands
tel:       +31 40 27-43166   *** SINCE 10-Feb-2005 ***
fax:      +31 40 27-44004
email: sebastian.egner@xxxxxxxxxxx








srfi-71-request@xxxxxxxxxxxxxxxxx

17-05-2005 14:26

       
        To:        Sebastian Egner/EHV/RESEARCH/PHILIPS@PHILIPS
        cc:        srfi-71@xxxxxxxxxxxxxxxxx
        Subject:        Re: what about dropping rest-lists?

        Classification:        




Sebastian Egner <sebastian.egner@xxxxxxxxxxx> wrote at 2005-05-17T10:51:31+0200:
> And if you really need the rest-list thing (the day will come),
> the meaning will at least be obvious.

How about a keyword named "rest", with parens around the keyword and
variable identifier?  The parens emphasize to human readers that the
"rest" name is in a keyword position and therefore should not be
mistaken for a variable identifier?

   (let ( (a b c d      (values 1 2 3 4)) ) c)  ;=> 3
   (let ( (a b (rest x) (values 1 2 3 4)) ) x)  ;=> (3 4)
   (let ( ((rest x)     (values 1 2 3 4)) ) x)  ;=> (1 2 3 4)

   (let ( (a b (rest x)    (values 1 2 3 4)) ) x)     ;=> (3 4)
   (let ( (a b (rest rest) (values 1 2 3 4)) ) rest)  ;=> (3 4)

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