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World: r3wp

[Parse] Discussion of PARSE dialect

Geomol
5-Feb-2008
[2364]
Or I should just stick with /at, because that's the word, we usually 
use to position ourselves within a series. (And the ram can be seen 
as a series.)
btiffin
5-Feb-2008
[2365]
/skip would be the rebolious name I think, but /org would resonate 
with me as well.
Graham
5-Feb-2008
[2366]
Elite was done on the C64 as well as other computers of that era, 
so would have been done in 6502 assembler.
Geomol
6-Feb-2008
[2367]
Yes! :)
From http://www.bbcmicrogames.com/acornsoft.html

It has been ported to just about every other platform out there however, 
it appeared first on the BBC.

The BBC had a 6502 too, and it's the platform, I'm testing up against, 
so let's hope, it all work out well.
Gregg
6-Feb-2008
[2368]
/at is probably fine.
Robert
8-Feb-2008
[2369]
Is there an emulator for this Elite release?
Henrik
8-Feb-2008
[2370]
I'm a little stuck here with a simple problem:

a: func [v] [

  parse v [
 
    any [
      'a (prin "a")

      | 'b (prin "b")
      | 'c (prin "c")

      (prin "-")

    ]
 
  ]

]

>> 

a [a b c c a]
abc-c-a


I want to print the dash after every letter. Do I have to include 
it after each word?
Oldes
8-Feb-2008
[2371x2]
a: func [v] [
  parse v [
    any [
    	[
        	'a (prin "a")
      		| ['b (prin "b")]
      		| ['c (prin "c")]
      	]
      	(prin "-")
    ]
  ]
]
a: func [v] [
  parse v [
    any [
    	[
        	'a (prin "a")
          | 'b (prin "b")
          | 'c (prin "c")
      	]
      	(prin "-")
    ]
  ]
]
Henrik
8-Feb-2008
[2373]
beautiful, thanks
Geomol
8-Feb-2008
[2374]
Robert, there's no emulator written in REBOL, that can run Elite, 
afaik. But there are emulators emulating the BBC computer, if that's 
what you mean, and they can run Elite. I use an emulator called BeebEm3.
PatrickP61
23-Feb-2008
[2375x2]
I have a question on the above parse by Oldes on Feb 8th.  
If you feed in a [a b c d e f] you will get a-b-c-==false

How can you change the parse so that it will put a dash in between 
all characters, without defining each character?
Now that I think of it, I would not even use a parse to do that. 
 But what could I do if I wanted only a subset of characters to show 
up without defining them all
BrianH
23-Feb-2008
[2377]
Patrick, in answer to your first question:
parse [a b c d e f] [
    set x word! (prin form x)
    any [set x word! (prin join "-" form x)]
]
PatrickP61
23-Feb-2008
[2378]
Super -- Thanks for the info.  I'm still learning about parse!
BrianH
23-Feb-2008
[2379]
You have to remember to structure your rules using LL style. Do you 
notice that I checked for one word first, then looped over the subsequent 
words? That was to avoid putting the "-" after the last word as well. 
Parse uses right recursion - not like yacc, which uses left recursion.
PatrickP61
23-Feb-2008
[2380]
I was just wondering about the trailing dash, but thought that could 
be handled in a different step.  Your method is cleaner.
BrianH
23-Feb-2008
[2381x2]
replace/all form [a b c d e f] " " "-"
Cleaner yet.
JohanAR
2-Mar-2008
[2383]
Can anyone help me why the following appears to work, but still returns 
false?

data: [ table [1 2 3] [4 5 6] ]

parse data ['table some into [ some [ set n integer! (print n) ] 
(print "-")] ]
Graham
2-Mar-2008
[2384]
do you need an 'end ?
JohanAR
2-Mar-2008
[2385x2]
just found out that this seems to work, but I don't really see why 
I have to include end. As I've understood "into" is supposed to fail 
and continue if the next item isn't a block!


parse data ['table some into [ end | some [ set n integer! (print 
n) ] (print "-") ]  ]
Ahh, another block around the into statement did the trick :P Thanks 
for the help though


parse data ['table some [ into [ some [ set n integer! (print n) 
] (print "-") ] ]  ]
[unknown: 5]
4-Mar-2008
[2387x4]
shouldn't datatype! be included in rule block parsing?
how do you do this:

blk: ["somestring" string!]

We can't do:

parse blk [string! datatype!]

and get a match.
I see I can do a reduce on the blk when passed to parse and get it 
true but not sure that is safe for my situation.
be nice if there was a lit-type!
Henrik
4-Mar-2008
[2391x2]
string! is considered a word here. you must provide the datatype 
in its serialized state:

parse ["something" #[datatype string!]] [string! datatype!]
same if you use none or other things that would be considered words 
in an unreduced block.
[unknown: 5]
4-Mar-2008
[2393x2]
I don't get what you mean by serialized state
>> parse ["something" #[datatype string!]] [string! datatype!]
** Syntax Error: Invalid construct -- #[

** Near: (line 1) parse ["something" #[datatype string!]] [string! 
datatype!]
Henrik
4-Mar-2008
[2395]
>> blk: ["something" string!]
== ["something" string!]
>> type? second blk
== word!
>> type? second reduce blk
== datatype!
 ; this you know, right? OK...
[unknown: 5]
4-Mar-2008
[2396x5]
I guess you mean datatype! with the "!"
yes Henrik
What I'm trying to avoid is any reducing
I dont' want any execution of code as I don't know what might be 
passed by the user
But I still need to validate the passed block
Henrik
4-Mar-2008
[2401]
>> mold/all string!
== "#[datatype! string!]"
>> blk: ["something" #[datatype! string!]]
== ["something" string!]
>> type? second blk
== datatype! ; voila :-)
[unknown: 5]
4-Mar-2008
[2402x3]
didn't know mold/all did that for string!
cool Henrik
I think that could work
Henrik
4-Mar-2008
[2405]
your "lit-datatype" is actually serialization. it exists for everything 
that otherwise would lose its datatype inside a block
[unknown: 5]
4-Mar-2008
[2406]
nice.
Henrik
4-Mar-2008
[2407]
mold/all will display how to serialize something so you don't need 
to reduce a block to get the right datatype in there.
[unknown: 5]
4-Mar-2008
[2408]
yeah I see which is exactly what I'm looking for.
Henrik
4-Mar-2008
[2409x2]
>> type? first [none]
== word!
>> type? first [#[none]]
== none!
a great and valuable tool (also speeds some things up)
[unknown: 5]
4-Mar-2008
[2411x3]
yeah I knew that one but didn't think about that for datatypes.
Yes greatly
It's gonna help me for what I'm doing.