I was proposing this on irc too... multiple retain stacks that you can
create and name on your own. And then also important is that stacks would
have not just push, pop functionality but also peek (so that value stays on
stack)
but I don't like your syntax that much, why would you have to define them
and use some structure (block) where there I don't see the need for it.
>people (could silently create and PUSH on them if they aren't yet created,
or a special syntax could be made for this to be)
people> (POP)
people|> or people (or something else for PEEK)
best regards,
janko
On Sun, Apr 6, 2008 at 11:41 PM, Maxim Savtchenko <[EMAIL PROTECTED]> wrote:
> I have mixed feelings about extra/locals library. It is good to have
> local named storage, but current design of extra/locals looks very
> "lispish" (FP-style immutable variables). I think, there is a way to
> make it closer to Factor stack-shuffling paradigm. So I have a
> suggestion. What if we can use not local variables, but local
> additional retain stacks, just like ">r" and "r>"? Let me show you
> this concept on example from recent Slava's blog-post:
>
> :: julian-day-number>date ( n -- year month day )
> #! Inverse of julian-day-number
> [let* | a [ n 32044 + ]
> b [ 4 a * 3 + 146097 /i ]
> c [ a 146097 b * 4 /i - ]
> d [ 4 c * 3 + 1461 /i ]
> e [ c 1461 d * 4 /i - ]
> m [ 5 e * 2 + 153 /i ] |
> 100 b * d + 4800 -
> m 10 /i + m 3 +
> 12 m 10 /i * -
> e 153 m * 2 + 5 /i - 1+
> ] ;
>
> This is how it looks with lisp-style locals. And here is my suggestion:
>
> : julian-day-number>date ( n -- year month day )
> #! Inverse of julian-day-number
> [rest n a b c d e f | >n
> n 32044 + >a
> 4 a * 3 + 146097 /i >b
> a 146097 b * 4 /i - >c
> 4 c * 3 + 1461 /i >d
> c 1461 d * 4 /i - >e
> 5 e * 2 + 153 /i >m
> 100 b * d + 4800 -
> m 10 /i + m 3 +
> 12 m 10 /i * -
> e 153 m * 2 + 5 /i - 1+
> ] ;
>
> "[rest" - is fo REtain STacks. It creates additional local stacks with
> accessors to them. Each stack ("x" for example) have three accessors.
> Traditional ">x" and "x>" with semantics of ">r" and "r>". And
> abbreviation "x" with semantics of "x> dup >x". At the end of "[rest
> ... ]" block remaining values on additional stacks are simply
> dismissed. Looks good for me.
>
> This raises major question. Is it possible to compile efficient code
> with more than one retain stack?
>
> Maxim Savchenko.
>
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