World: r3wp

I know that due to efficient represeantion of values with 16bytes 
gives a constraint. But it would be really cool if rebol adopted 
the tower of numbers from Scheme.

Rebol offers a way for handling molding of new data types that could 
be exploited. We could mold an inexact deci! using something like 
#[deci! [precision: 4  value: 1.33333333]]

...the problem with deci! could be address in the same way that plt-scheme 
does...

  - there is no problem with deci!, it is decimal! that has got a problem

Ah. Well then apply my comments to decimal!

do you like this: any [1 true] ; == 1 ?

sorry, bad cut and paste, forget about it

what would you prefer this expression to return, 1 or 2?:

		loop 1 [
			f: func [x] [
				either x = 1 [
					loop 1 [f 2]
					2
				] [break/return 1]
			]
			f 1
		]

I take "either is fine" as a possible answer too

I prefer "2".

sorry, I should have posted my question to Rebol3 group, probably, 
because it is about the new behaviour mainly

2 too. the result of "f 2" is thrown away, the last value 2. should 
be returned. i would  not expect some side-effect here.

The break/return should only change that with a 
  f: func[[throw] x] 
IMO.

Maybe without even give an error.

(continue in Rebol3 group)

I think this is a bug ...

to-local-file what-dir

it removes the trailing "/"

Yep, the DOS/Windows way of representing directories is buggy. Rebol 
is not at fault here.

what's the easiest equivalent to:

>> set to-path [a b c] 7 ; doesn't work

where the block may be a set of arbitrary words in an arbitrary object.

Certainly not the most elegant sollution:
set-path: func [pth val /local rslt][
	rslt: copy []
	head insert/dup head rslt [in get] -1 + length? pth

 repeat i length? pth [append rslt to block! form to path! reduce 
 ['pth i]]
	set do bind rslt 'pth val 
]

>> a: context [b: context [c: 0]]
>> a/b/c
== 0
>> set-path [a b c] 7
== 7
>> a/b/c
== 7

wow, that's a lot of stuff alright...

well, it seems to work, thanks :-)

do reduce [to set-path! [a b c] 7]

hehe I knew there's some simple way :)

ladislav, I did that one, but somehow I have trouble binding the 
result to the original object

yes, the word 'a must have proper context for this to work

do reduce bind [to set-path! [a b c] 7] 'a does not seem to work

rebolek: it doesn't handle paths with indexes in them. I don't always 
store objects inside objects, but also blocks of objects. are there 
ways around that?

do reduce bind [to set-path! [a b c] 7] 'a does not seem to work

 - right, that is not supposed to do anything meaningful, it simply 
 keeps the context the word 'a had

>> a: context [b: context [c: 0]]
>> do reduce [to set-path! [a b c] 7]
== 7
>> a/b/c
== 7

If 'a does not have meaningful context, then bind [...] 'a cannot 
repair the situation

but 'a does have a meaningful context. I'll have to try a different 
approach.

load mold reduce [to set-path! ... ] seemed to work

You shouldn't have to do that (load mold). Can we see a bit more 
of your code ?

rel-obj: make object! []

add-relation: func [path-block [block!] /local p v w] [
  p: to-block 'rel-obj
  parse path-block [
    any [
      [set w word! (
        unless all [

          find either object? do to-path p [first do to-path p][[]] w
          insert tail p w
        ] [

          do load mold reduce [to set-path! p make do to-path p reduce [to-set-word 
          w none]]
        ]
      ]
   ]
]

I'm not sure it's enough...

it's only a small part of the function

usage example of add-relation ?

eg..  add-relation [...]   <-- what's in the block.
And what's the result supposed to be ?

I'm rewriting my relations engine, if you remember that one.


I need to traverse rel-obj via paths, so I store the path as words 
in a block. This is in order to maintain the current position in 
a deep object.


The input can be any arbitrary path of words and values. If the values 
or words don't exist, they will be created on the fly. That's what 
I use 'p for.

Ah I see.

the code with the do load mold... is supposed to insert a new object 
at the path position if the current value at that point is 'none. 
I removed some of that "if none?" logic for clarity.

So rel-obj can start out completely empty, but fill with values afterwards 
?

yes. an example could be if rel-obj was empty:

add-relation [users male "Joe"]
add-relation [users female "Jenny"]

later on, when you look it up, it's supposed to look like:

get-relation [users]
== [male female]
get-relation [users male]
== ["Joe"]

You can go deep:

add-relation [users male "Joe" age-group "Senior"]

And you can do reverse relations:

add-relation [age-group "Senior" users "Joe"]

the rules and structure is completely arbitrary, which is one of 
the stronger points of the relations engine.

however the current version forces you to use a path block structure 
of [word value word value word value...] which forces you to choose 
a value that will not be used for branches where only one path should 
exist. that's why I'm doing a rewrite.

I suspect you are assuming you can extend objects, which cannot be 
done in rebol currently.

the relations engine already does that :-)

but I need some more freedom in the path block

No, I mean extending objects and keeping the same object.