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Vladimir Vasilyev
@9214
@nedzadarek do you understand how words/context mechanic works?
nedzadarek
@nedzadarek
Yes, more or less:
b: 42
b-context: context? 'b
b-context/b
Vladimir Vasilyev
@9214
@nedzadarek do you understand how variables work, as in other mainstream languages?
nedzadarek
@nedzadarek
Yes
Vladimir Vasilyev
@9214
I tend to interpret your "Yes, more or less" as "No".
@nedzadarek do you think that words/context mechanic is different from variables mechanic, or do you think that they are the same?
nedzadarek
@nedzadarek
Similar I guess... but I cannot say with 100% certainty because I don't understand a lot languages that deep.
Vladimir Vasilyev
@9214
So you don't know/understand the difference, but you keep arguing that words are variables, as in other PLs?
nedzadarek
@nedzadarek
There are a lot of languages that uses "variable". Every language differs. Variable = value that can change over time.
Vladimir Vasilyev
@9214
@nedzadarek but variable itself is not a value, right?
Words is a value that can indirectly refer to other values. Variable is just a pairing between identifier and memory location.
Word can refer to (be bound to) different contexts, but context is not a value (in "variable" sense) itself, and not a memory location where this value resides.
nedzadarek
@nedzadarek
Similar stuff you can do in Ruby (you don't do this very often but... you can). @secret is still a variable (taken from: http://ruby-doc.org/core-2.4.0/Binding.html ):
class Demo
  def initialize(n)
    @secret = n
  end
  def get_binding
    return binding()
  end
end

k1 = Demo.new(99)
b1 = k1.get_binding
k2 = Demo.new(-3)
b2 = k2.get_binding

eval("@secret", b1)   #=> 99
eval("@secret", b2)   #=> -3
eval("@secret")       #=> nil
Vladimir Vasilyev
@9214
unnamed0.png
@nedzadarek what you seem to call a "variable" is a binding + relation between symbol ID and value inside context.
Which doesn't make much sense, because context can contain only one such pairing between symbol ID and value, i.e. it's implied.
Vladimir Vasilyev
@9214
Word is a separate value (any-word!), and context is provided by separate values (object! or function!). Binding is a relation between two separate entities, which you can manipulate at run-time (words and functions/objects). Variable, on the other hand, is a way to reference a value, but not a relation between the two values.
Vladimir Vasilyev
@9214
It's a bit different under the hood (there're nodes, symbol table and symbol IDs, value slots, etc), but the idea is the same.
Vladimir Vasilyev
@9214

@nedzadarek since "variable is a way to reference a value", "variable" (in your interpretation) can be either:

  • a way to reference a value that provides a context (but that's not a "variable", it's a "binding");
  • a way to reference a value in a context (which is done indirectly by word's binding and implied);
  • how symbol ID is related to a value slot (which is just a key/value association, loosely speaking).

Word is not a variable in any of these cases, it never refers to the value directly, it's always refers to a context provided by some value (either by object on the heap or by function on the call stack).

Whichever terminology you personally use is completely up to you, but if you're willing to communicate with other Reducers in established (and productive) manner, while avoiding possible confusion of newcomers -- stick to our conventions and wordings.
Christopher Ross-Gill
@rgchris
@9214 Or just put caution tape on every script until a native version of USE appears.
Vladimir Vasilyev
@9214
@rgchris no one reads caution tapes nowadays.
Christopher Ross-Gill
@rgchris

@ne1uno

did rebol have a bigger problem leaking context?

Currently Rebol 2 and Red are little different in this regard.

use seems like a solution in search of a problem in red

An interesting way of looking at it. I've long found it a very tidy way of creating micro-contexts. With Rebol 3's tighter control on context, I've found it a useful way of tracking word useā€”even within modules.

hiiamboris
@hiiamboris
is it ok that replace treats it's pattern as a parse rule only when /deep refinement is provided?
it's doc-string seemingly totally omits this specific
Vladimir Vasilyev
@9214
@hiiamboris yes, look at the source.
hiiamboris
@hiiamboris
yes, that's what I did to get to the conclusion
hiiamboris
@hiiamboris
@hiiamboris You can always use (pick a 'y) < (pick b 'y).
>> p: 2x3
== 2x3
>> pick p 2
== 3
>> second p
== 3
>> pick p 'y
*** Script Error: value out of range: y
*** Where: pick
*** Stack:
maybe there was an intent to make this work, maybe not, but just sayin... it doesn't work
lepinekong
@lepinekong_twitter
I have a weird case for set: it works with one element but not with 2 : * Script Error: forall does not allow word! for its 'word argument
P: context [

    F: [
        P1: [
            name: "John"
        ]

        P2: [
            name: "Mary"
        ]    
    ]

]

set [list1 list2] compose [
    (words-of (Context (P/F)))
    (values-of (Context (P/F)))
]

; this works
set [list1] compose [
    (words-of (Context (P/F)))
]

; this doesn't work
forall list1 [
    probe list1/1
]

forall list2 [
    probe list2/1
]
Vladimir Vasilyev
@9214
@lepinekong_twitter both list* words are bound to other words (P1 and P2, respectively).
I guess that's what you want instead:
P: context [
    F: [
        P1: [name: "John"]
        P2: [name: "Mary"]    
    ]
]

set [list1 list2] reduce [
    words-of  context p/f
    values-of context p/f
]

forall list1 [probe list1/1]
forall list2 [probe list2/1]
lepinekong
@lepinekong_twitter
@9214 ah yes thanks, have always difficulty to understand bind stuff :worried:
Vladimir Vasilyev
@9214
@lepinekong_twitter there's zero "bind stuff" here.
Examine the result of compose application and you'll probably figure out that it's not what you expected.
You should have used compose/only instead, which composes nested blocks "as-is" (though compose is superfluous here, as reduce can do the same job just fine). Moreover, I don't get why you need multiple parenthesis nestings.
lepinekong
@lepinekong_twitter
@9214 thanks I never know when to use reduce or compose, will have to think about it
Vladimir Vasilyev
@9214
@lepinekong_twitter use reduce whenever you need a block of evaluated expressions, and compose when you have a "template" data with forms to fill in.
lepinekong
@lepinekong_twitter
@9214 It is now part of my ever growing list of all troubleshootings :smile: https://i.snag.gy/obuyZO.jpg
Vladimir Vasilyev
@9214
@lepinekong_twitter don't push yourself too hard :) is that a list of "flashcards"?
GiuseppeChillemi
@GiuseppeChillemi

@greggirwin

One of the great and terrible things about Redbol langs is their chameleon ability. @nedzadarek, a great many details are hidden under a facade that makes Red quickly accessible to people, but there is the risk that they will see it "as just like X", when it really isn't.

That has been just my problem. The original REBOL core manual did not a good job on letting me forget about variables, pointer and classic OOP.

Now I read this section with great interest. I need just only to find how to bookmark discussions.
Vladimir Vasilyev
@9214
@GiuseppeChillemi click on timestamp of the message you're interested in and copy its link from the address bar. Like this:
https://gitter.im/red/help?at=5acd1de3080a3850531a9b18
GiuseppeChillemi
@GiuseppeChillemi
@9214 I have clicked everywhere but timestamp ! Thanks !
GiuseppeChillemi
@GiuseppeChillemi

@9214

unnamed0.png

@nedzadarek what you seem to call a "variable" is a binding + relation between symbol ID and value inside context.

What is SYMBOL ID ? I am getting confused. Could you make a graph adding real words, blocks and arrows to this structure and also underliyng C like rappresentation of the data structure ?

Vladimir Vasilyev
@9214

Word reference its context through a node (just a special intermediate structure) and has a symbol ID, which is an index in a symbol table. Context, in turn, is just a two-column table: first column is for symbol! slots, second one is for any-value! slots.

When a word is evaluated, a value is fetched in the context pointed by that word, from the value slot that correspond to the symbol ID held by the word. In that sense, words is an instance of an internal symbol! datatype: word = a context reference + a symbol ID.

Symbol table, as I understand it, is nothing more than block of symbol! cells, one per Red session currently (should be one per module in the future). Symbol ID is an index of a cell in that block. symbol! cell holds a UTF-8 representation of a word (its "spelling", it's actually a pointer to a string buffer, again through node) and an alias field. If word is an alias of the other word (think case-insensitivity), this field will hold an index of the original word.

Ryan Cole
@prapro
Basically it's The Force. https://youtu.be/x2YQJsbbWNA
Vladimir Vasilyev
@9214
https://gitter.im/red/help?at=5acd2aa75f188ccc154fc0b2
:point_up: I think it should be " ... two-column table: first column is for symbol IDs ..." instead, but the idea is the same.
BeardPower
@BeardPower

The data of a type struct is stored in a cell, which is a red-value. These structures are 128bit slices on the stack (4 32bit integers). A cell consists of
header
data1
data2
data3

Which are filled/type-casted to the appropriate types.

Vladimir Vasilyev
@9214
Cells and slots are synonyms, though "cell" is used as a low-level term. Cells are allocated from the heap as block! buffers.