World: r3wp
[Parse] Discussion of PARSE dialect
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Maxim 24-Dec-2008 [3369] | the idea being, as long as rule1 matches, return the AT of that rule, executing the second one there. |
BrianH 24-Dec-2008 [3370x2] | ? |
It sounds like AT. | |
Maxim 24-Dec-2008 [3372x3] | the differentiation is quite subtle, and I am pretty sure that the rejected was mine hehehe. |
but new that I have rebuild remark WITH parse and that I have read the proposals, I am in a much better state to explain it, I think. | |
but it will need precise thinking... something I can't cook up in a matter of seconds without generating a lot of short questions like the above. | |
BrianH 24-Dec-2008 [3375] | Cool. I understand everything on that page, so your timing is good for a discussion :) |
Maxim 24-Dec-2008 [3376x4] | a better way of calling could be 'UNFOLD if you think about it functionally. |
remark is the basis for my proposal. I can already to what I propose in parse v2... but I beleive it could be done so simply and could reduce your first example (the recursive file list) to a 5 line affair. | |
maybe even less ;-) | |
so I'll try to cook up an example of how it would be used, and the effect it would have... then you can tell me if I'm nuts ;-) | |
BrianH 24-Dec-2008 [3380] | I finished the Parse Proposals cleanup again. Enjoy! |
Maxim 24-Dec-2008 [3381x2] | so, I put a lot of thought into it, and with the new stuff... especially 'CHANGE 'AT 'ONLY , the problem with 'UNFOLD is that its too problem specific. the general idea was to build a system which basically does an: rule: [ any [at change only [ rule ]] | skip] the problem is that what to skip and what to change, differs from problem to problem, and since these are tied up within subrules, they become hard to use within a generalized procedure. in R2 the above is pretty harsh to implement, although it can be done... with the use of the 'USE operation, these words already make recursivity and stack issues pretty easy to tackle.. |
hehe... synchronicity. | |
BrianH 24-Dec-2008 [3383] | CHANGE doesn't work the way you think it does - look again. |
Maxim 24-Dec-2008 [3384] | no I really did a good read, and understand your example... its the 'AT which does the trick. |
BrianH 24-Dec-2008 [3385] | You are missing a parameter in your example. |
Maxim 24-Dec-2008 [3386x2] | along with 'ANY which reparses until nothing was changed... that's the basis for my original proposal... it reparses until nothing changed... |
oh... sorry didn't get that... yes there would be an extra paren there. | |
BrianH 24-Dec-2008 [3388x2] | CHANGE works like that already. If the rule it is matching fails, the change fails. |
I'm probably not getting you... | |
Maxim 24-Dec-2008 [3390] | but, in R2, I'm not using it for some reason I don't remember... I actually use the change/part within a paren and manually set the series using the :here trick. |
BrianH 24-Dec-2008 [3391] | Right. All of the PARSE proposals have (awkward) R2 equivalents :) |
Maxim 24-Dec-2008 [3392x3] | ahh... its all string based. |
yep... cause I've been doing all of them in remark for a year :-) | |
although the 'USE really makes a BIG capability boost in PARSE. | |
BrianH 24-Dec-2008 [3395] | I had to clean up a few REBOL 2 assumptions in the proposals list, mostly by Peta, through no fault of their own :( |
Maxim 24-Dec-2008 [3396x2] | so I'll go back to the batcave and continue working on remark v2, and some other stuff... I want to release since a long time |
its fun to be able to read all that stuff about parse and *get* it. | |
BrianH 24-Dec-2008 [3398] | Yeah, the R2 equivalent of USE is the most awkward :( |
Maxim 24-Dec-2008 [3399] | not so long ago, it used to be magic... nothing to big, or I'd get really lost. |
BrianH 24-Dec-2008 [3400x3] | The biggest problem you would have if compiling the new rules to their R2 equivalents would be to generate all of the intermediate variables and make sure their bindings are not corrupted on recursion. |
If you weren't careful you could easily overflow system/words :( | |
Must go now - it's been fun :) | |
Maxim 24-Dec-2008 [3403] | yes cool. ciao... |
BrianH 29-Dec-2008 [3404] | I finished the Parse Proposals cleanup again. Enjoy! |
GiuseppeC 29-Dec-2008 [3405x2] | I have read the cleanupped version. I like the "To-Thru" proposal to match for multiple ends but I have read that full grammar could not be used for "performance reasons". |
However the proposal is really big and I think that implementing it would not be so easy and fast. Will we see it complete at the end of 2009 ? It is only Carl working on it :-( | |
BrianH 29-Dec-2008 [3407x2] | The real advantage to the TO/THRU enhancement comes when it lets you avoid creating charsets, which are a lot less useful with Unicode. It should be pretty easy to implement. |
I think that the proposals are more than Carl was thinking they would be - apparently he had forgotten the previous proposal lists. I don't think that it will be too much of a problem though, as there are not really that many proposals that are likely to be accepted. Some are competing proposals, of which only one would be chosen. Also, there aren't that many proposals overall - they are just thoroughly specified. | |
GiuseppeC 29-Dec-2008 [3409x3] | Lets see how things evolves. Proposal are very interesting as they would easy a lot of work on building parse rules. Everything is silent apart some blog messages where I have read for the first time the word "Beta" connected with REBOL3. |
(*ease) | |
Good night. Here in Italy is 20 past 1AM. | |
BrianH 29-Dec-2008 [3412x4] | My main concern is that Carl's main requirements of the proposal process have been ignored in some cases: - That the proposals be concisely specified. The Purpose and Importance statements should be one sentence each. - That there be no discussion of theory. - That there be no specification of equivalent rules. - That all discussions happen outside of the wiki. - That this is a proposals page, not documentation. |
While I appreciate the speculative documentation, it will need to be moved to another page once the proposals process is done. | |
As it is, I hope Carl will read a paper that long when he gets to the point of taking on PARSE. | |
The whole point of the proposals process was to prevent exactly what happened, so in that respect I failed. | |
PeterWood 29-Dec-2008 [3416] | If Carl sticks to his word in his intial request all the proposals will be rejected: Each improvement will require test code be provided that would certify its correctness. No test code, no improvement. (Sorry... you often ask me what you can do to help. Please don't put the burden of testing such changes on me.) |
BrianH 29-Dec-2008 [3417x2] | The test code hasn't been written yet. |
The initial request was not the blog post - that came later. | |
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