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World: r3wp

[!REBOL3]

Geomol
21-May-2011
[8798]
Makes sense.
Kaj
21-May-2011
[8799x4]
Putting words in a context

 is binding. That's very different from the symbol table, which you 
 could say "binds" symbol strings to integer IDs
If you can't read Finnish, it means the Finnish symbols are not bound 
to values in contexts in your head. Closing the book and erasing 
the symbol table is equivalent to quitting the REBOL proces, which 
does release the memory
I'm sure some Finnish words are also words in Danish, so forgetting 
the symbol table wouldn't help your situation :-)
I'm sure because my name is one of them...
Pekr
21-May-2011
[8803]
I prefer Finnish Vodka, and Finnish music :-)
Ladislav
21-May-2011
[8804]
John, you are missing some things others know and find obvious. For 
example, do you know the answer to the following question?

    What is the ratio between

        stringn: func [n] [head insert/dup copy "" #"a" n]


        word: to word! stringn 1 t1: time-block [equal? word word] 0,05

        word: to word! stringn 1000 t2: time-block [equal? word word] 0,05
        t2 / t1

compared to


        string: stringn 1 t1: time-block [equal? string string] 0,05

        string: stringn 1000 t2: time-block [equal? string string] 0,05
        t2 / t1
?
onetom
21-May-2011
[8805x2]
time-block? u mean delta-time?
(your naming is more intuitive though... it's also 'time in bash...)
Geomol
21-May-2011
[8807x2]
Thanks, Ladislav. Good examples!


The thing, I missed, was that REBOL has this extra internal data 
structure to hold symbols (words), I though, just the contexts was 
used for that. So comparing words (that are not bound to any context) 
are much faster than comparing strings in REBOL. I see different 
possibilities, depending on implementation. If a word is changed 
to the result from a hash calculation, then two different words might 
give the same result, right? It's unlikely, but it could happen. 
That's why map datastructures are combined with lists, when two different 
hash calculations give same result. The other possibility is, that 
words are changed to pointers pointing to their entry in the map 
(hash table). Do you know, what of the two, REBOL implement? In other 
words, could two different words be equal in REBOL?


About the strings, then it's possible to do kind of the same with 
hashing. Lua does that. If you have two different but identical strings 
(same string content) in Lua, they share the same memory area. Hashing 
is involved, and I guess, comparing string would be equal fast as 
comparing words, if REBOL did the same. (unless words are exchanged 
with the result from the hash calculation, but then two words might 
be equal)
After a little testing, it seems, words are changed to a hash result, 
and REBOL gives an error, if two different words give same result:

>> s: "abcdefghijklmn"

>> forever [if equal? a: to word! random s b: to word! random s [print 
[a b]]]
** Internal Error: No more global variable space

The error comes really fast.
Kaj
21-May-2011
[8809]
Petr, Nightwish? :-)
Geomol
21-May-2011
[8810x3]
Above test is in R2.
R3 keeps going and can't be stopped with <Esc>.
<Esc> + <Ctrl>-c seem to stop it.
Kaj
21-May-2011
[8813x2]
Global variable space should be the special object holding global 
values in R2. That's not the symbol table, either
My guess is that it must do more useless binding than R3
Geomol
21-May-2011
[8815]
You're right. to word! put it in system/words, I need to do to block!, 
I guess.
Kaj
21-May-2011
[8816]
Maybe to-lit-word works
Geomol
21-May-2011
[8817]
In R2:

s: "abcdefghijklmn"

forever [if equal? a: to block! random s b: to block! random s [print 
[a b]]]

rebol-console: line 2:  5658 Floating point exception./rebol --noviewtop

A crash. Interesting! :)
Kaj
21-May-2011
[8818]
Indeed
Geomol
21-May-2011
[8819]
to lit-words! also put it in system/words in R2.
Kaj
21-May-2011
[8820x2]
That's probably one of the things optimised away in R3
It's such a shame it's stalled
onetom
21-May-2011
[8822]
I think, Carl will return soon and he will open source R3.

He must have a hard time doing that other job, but probably he will 
experience the bright side of the open collaboration too.

Im expecting him to realize that he can actually help the world effectively 
if he can unleash the power us, the long time fans of rebol.
Kaj
21-May-2011
[8823x2]
Don't hold your breath
John, to keep your mind on the edge of the cliff, did you know about 
the global series table? :-)
Geomol
21-May-2011
[8825]
Not sure, what's that?
Kaj
21-May-2011
[8826x5]
Quite similar to the global symbols table, the existence of a global 
series table can be deduced, from the R3 extensions interface
A series value does not include an index. Only a reference does. 
So that's one indirection, from a value slot (with an index) to a 
series value
But there must be another indirection, from the series value to the 
actual storage location of its item slots, because the item storage 
can't be counted on to stay at the same memory address over garbage 
collection and callbacks or multitasking, but it must be deduced 
that the series value can be counted on to stay at the same memory 
address
So there must be a table of series descriptors apart from the actual 
series content
Maybe it doesn't really need to be a global table, but it seems very 
convenient for the garbage collector
Geomol
21-May-2011
[8831]
No, haven't heard of that.
BrianH
21-May-2011
[8832]
It wouldn't need to be a global table, it could be a heap space dedicated 
to series descriptors (a typed array in memory). Same purpose, more 
likely implementation. Precise collectors are often implemented with 
type-specific heap spaces, since it reduces fragmentation when you 
don't have a copying or compacting collector - REBOL's collector 
doesn't move values, supposedly. REBOL could get away with heap spaces 
for block data, string/binary data, and descriptors (maybe both object 
and series in the same heap space); there might be more, but adding 
more can make the memory management more complicated.
Kaj
21-May-2011
[8833]
I'm not sure how that differs from my description
BrianH
21-May-2011
[8834]
can't be counted on to stay at the same memory address over garbage 
collection

 - as far as I know this has never been demonstrated. The performance 
 characteristics of REBOL's garbage collection are more consistent 
 with mark-and-sweep, and there hasn't been any indication that it 
 compacts or copies. Series reallocation on expansion does copy though. 
 Plus, there is a bunch of indication that R3 isn't yet task-safe 
 and that callbacks can choke on shared data too. Aside from that, 
 your argument's good, and your conclusion more so.
Kaj
21-May-2011
[8835]
Well, I wouldn't count on it, but indeed, what the extensions documentation 
specifies is that series can move when they are changed. It's all 
very vague, but if the collector doesn't compact as you say, it would 
be restricted to expanding series beyond the internally allocated 
memory region
Ladislav
21-May-2011
[8836x5]
time-block? u mean delta-time?
 I mean TIME-BLOCK:

http://www.fm.tul.cz/~ladislav/rebol/timblk.r
could two different words be equal in REBOL?
 - in my opinion, that would be a bug
(unless intended, using aliasing)
heap spaces for block data, string/binary data,

 - there is absolutely no reason to have different spaces for strings 
 and blocks
aha, maybe there is
BrianH
22-May-2011
[8841x2]
If you allocate strings only in multiples of 128 bits and aligned 
the same as blocks, fragmentation wouldn't be a problem if they are 
allocated in the same space. It would be a waste of resources for 
strings though, as even a single-char string would take 16 bytes 
of space.
Some memory management systems segregate the values by the size, 
with objects of similar sizes allocated from the same space, to cut 
down on fragmentation. Large enough objects are sometimes allocated 
on their own, in a seperate chunk of memory allocated from the OS. 
I haven't seen any indications that REBOL's memory management does 
this though.
Jerry
24-May-2011
[8843]
Why does SKIP accept LOGIC! and PAIR! as its OFFSET parameter? Thanks.
Geomol
24-May-2011
[8844]
pair! is for images, I think.
Jerry
24-May-2011
[8845]
I have the same guess. Geomol
Geomol
24-May-2011
[8846]
About logic, I guess, it's related to a wish to use PICK with logic 
argument. It works like this for SKIP:

>> skip [a b] true
== [a b]
>> skip [a b] false
== [b]

and you can use PICK instead of EITHER sometimes like:

value: pick [1 2] b > 1

instead of

value: either b > 1 [1] [2]
Jerry
24-May-2011
[8847]
SKIP with TRUE as its 2nd argument, which made me think it DID skip. 
SKIP with FALSE as its 2nd argument, which made me think it DIDN'T 
skip. With your PICK example, now I understand.