World: r3wp
[!REBOL3]
older newer | first last |
Geomol 5-May-2011 [8518] | Or better, as I'm not sure, I like get-words as function arguments (see source of quote): >> do first ['a/1] == a/1 |
Ladislav 5-May-2011 [8519] | as I'm not sure, I like get-words as function arguments - this formulation is unfortunate. What the spec block of the QUOTE function does is that it specifies how the argument expression is handled. In R3 it means "don't evaluate the argument". |
Geomol 5-May-2011 [8520] | Yeah, of course get-words can be function arguments. :-) As you said, get-words in function spec blocks. I'm also not too fond of lit-words in spec blocks. I know, functions like HELP and SOURCE works like they do because of this, but if used frequently, code will be less readable, as I see it. |
Ladislav 5-May-2011 [8521] | The QUOTE function is fine, and it is actually necessary, since e.g. there is no LIT-LIT-WORD argument, so, to obtain a lit-word, the most natural way is to use quote 'a |
Geomol 5-May-2011 [8522x2] | If it's necessary, then we need to come up with examples of functions, that take a lit-word as an argument. I can't think of any. |
Beside trivialities like TYPE? :) | |
Ladislav 5-May-2011 [8524x4] | that take a lit-word as an argument - that looks unrelated |
do we understand each other? | |
For example, the INSERT function can take a lit-word as an argument, if that is what you asked | |
...but why did you ask that? | |
Geomol 5-May-2011 [8528x2] | Yes, that's an example. I'm ok with writing insert blk to lit-word! 'a I asked, because you said, QUOTE is necessary. I don't see it as really necessary. |
(old discussion, I know) :) | |
Ladislav 5-May-2011 [8530x2] | insert blk first ['a] is much more reasonable than that (your example converts a word to a lit-word, and unnecessarily so. |
...because it first converts the said lit-word to a word (undesirably) | |
Geomol 5-May-2011 [8532] | well, if it works and do the job. And it's nice, there are more than one way to do things. |
Ladislav 5-May-2011 [8533x5] | ...and I do not think it has been discussed thoroughly, but, anyhow, I guess, that nobody objects against having lit-words or lit-paths. In that case, it is strange to object against QUOTE, especially taking into account, that QUOTE is much more universal, so, instead of saying get 'word we can always say get quote word |
I guess, that you feel, that the ' is much less universal (available only in some cases), while QUOTE is universal in R3 (always usable). | |
Why I wrote "QUOTE is necessary" - because that is the only way how to do it directly. Using the "double conversion method" you can do it usually as well, but that certainly does not count as a "direct method". | |
I even recall we used QUOTE to explain some issues to a beginner, which would be impossible to explain using the "double conversion method" | |
Moreover, the first ['a] method does not apply as a "direct method" as well, since it really performs some action, namely it gets the first value of a block, which is not a trivial operation, like QUOTE. | |
Geomol 5-May-2011 [8538] | If allowing get-words in spec blocks, then QUOTE is fine. I'm questioning allowing get-words in spec blocks. It can lead to uses as this: I make a function, that can do a paren! (in lack of better example, but it makes the point, I think): >> do-paren: [:p] [do p] I can try it on a paren: >> do-paren (1 + 2) == 3 Works ok so far, so I try having a var holding a paren: >> q: quote (1 + 2) == (1 + 2) >> do-paren q == 3 I got the feeling, I know how do-paren works, until I write: >> do-paren quote (1 + 2) ** Script Error: do is missing its value argument Hm, what if I use the old method: >> do-paren first [(1 + 2)] ** Script Error: p expected series argument of type: series pair event money date object port time tuple any-function library struct even... That's confusing, as I see it. (Example done in R2.) |
Ladislav 5-May-2011 [8539x2] | do-paren: [:p] [do p] - the only problem with the function is, that the function is so, that it can "do a paren", but only if that "paren" is already supplied as a value, i.e. not as an expression |
reformulation: is should have said: "only if the said 'paren' is not supplied as a result of an expression" | |
Geomol 5-May-2011 [8541] | I remember reading, parens are evaluated (an active type, I think you call it). It's a very fundamental thing. Breaking this rule make the code less readable. Is it really necessary? What natives or mezz have get-word arguments? Kinda the same with lit-word arguments (in the spec block). My guess is, Carl made those, so he could write: help add instead of help 'add |
Ladislav 5-May-2011 [8542x2] | Please, stop writing "get word arguments", they are not "get word arguments" |
Similarly, the "lit word arguments" are not "lit word arguments" | |
Geomol 5-May-2011 [8544x2] | right, what should we call them to not make confusion? |
Maybe "get-word func parameters"? | |
Ladislav 5-May-2011 [8546x2] | they are "unevaluated arguments" in case of the QUOTE function, and and "partially evaluated arguments" in case of e.g. the first argument of the FOREACH function. |
by "unevaluated" is meant "never evaluated", by "partially evaluated" is meant "sometimes evaluated, sometimes not evaluated" | |
onetom 5-May-2011 [8548] | (i didn't know about the :p where is it documented? otherwise i used the 'p notation many times. it even allows to add explanatory words to the parameters, so u can make a nice dialect by using the default 'do evaluator...) |
Geomol 5-May-2011 [8549] | The R2 doc for "get arguments" is here: http://www.rebol.com/docs/core23/rebolcore-9.html#section-3.3 |
onetom 5-May-2011 [8550] | thanks a lot. i thought i know the core docs in and out :) |
Geomol 5-May-2011 [8551x3] | :) I look in them now and then, as it's easy to forget many of the features in the language. |
About unevaluated lit arguments (or literal arguments, as Carl call them), the functions FOR, FOREACH, REPEAT and maybe more use them (I couldn't remember earlier when I posted). And yes, it's more convenient to write repeat i 10 [...] than repeat 'i 10 [...] But used in some cases, it's probably easier to create less readable code. I can imagine a language, where this is different. About the other type of unevaluated arguments (get arguments as Carl call them), I haven't found other functions than QUOTE, that use it. There must be others!? | |
there is no LIT-LIT-WORD argument, so, to obtain a lit-word, the most natural way is to use: quote 'a Some thoughts: So one use of this is to make it easier to e.g. insert a lit-word in a block. I come to think of how to insert a block in a block. We can't do: insert blk [a b c] as that will insert the 3 words, a, b and c, in blk. So I can write: insert blk [[a b c]] or insert/only blk [a b c] Why not use the same kind of thinking, when dealing with lit-words? So I can write: insert blk ['a] or maybe insert/only blk 'a (maybe the refinement should be called something else than /only). Now, the rule for INSERT should then be, that if it get a word (the lit-word, 'a, will be translated to the the word, a), it should change that to a lit-word, if it got the refinement too. Result is, that unevaluated get arguments can be avoided making the REBOL scanner/parser simpler. | |
BrianH 5-May-2011 [8554x2] | Geomol, if you agree with this model: >> do quote 'a/i == a/1 , put your agreement in http://issue.cc/r3/1434where it counts. |
As for functions with get-word arguments, the DO dialect used to need more of them, but in R3 most of those needs are handled by QUOTE. For other dialects though it is much more useful, as it prevents evaluation by the DO dialect when it is unwanted. It can be used on occasion in security situations if you want to block calculated values. Also, it could be used in a statically compilable subset of REBOL for the block arguments of all control and loop functions like IF and WHILE. | |
Geomol 5-May-2011 [8556] | No need, Ladislav already put it there. If that's for Carl to read through, it's an awful lot of information. |
BrianH 5-May-2011 [8557x4] | Consensus adds to the strength of an argument. Chiming in with an "I agree with Ladislav" on a potentially controversial issue reduces the controversy that might otherwise block it, especially if you are sometimes someone who disagrees with Ladislav effectively (which is pretty difficult to do). |
This has worked very well before with CureCode tickets and such. If Carl doesn't have a strong opinion either way, he will wait for consensus. | |
Back to QUOTE and get-word arguments... We need something like QUOTE, especially for set-*, *-paths, and functions, because these block an evaluation that may have side effects, or at least cause a value copy. Even if QUOTE is the only function with this evaluation model, it depends on DO supporting something like get-word argument evaluation in order to work at all. The alternative is to make 'quote a keyword in the DO dialect, which decidedly doesn't have keywords. So we can't get rid of get-word arguments altogether without ridding ourselves of QUOTE, and you'd get a bit of resistence from anyone who's used it if you want to do that. | |
If you want a SECURE 'get-word constraint that you can apply after QUOTE is defined, that will block some but not all function hacking attempts using function values. The "but not all" part is critical though, so we are better off from a security standpoint if developers aren't allowed to think of function values as being safe to call without precautions, since the consistency of the need for that precaution makes it more commonly applied. | |
Geomol 12-May-2011 [8561] | Is this because string implementation isn't finished? >> next "abc" == "^@^ Maybe related to UTF? |
Rebolek 12-May-2011 [8562] | This is on OSX? If yes, it's probably this bug http://curecode.org/rebol3/ticket.rsp?id=1870&cursor=1 |
Geomol 12-May-2011 [8563] | Yes, on OSX. Thanks! |
GiuseppeC 12-May-2011 [8564] | Are we still alone ? No news from/about Carl ? |
Geomol 12-May-2011 [8565x3] | Carl posted in that bug at 22-Mar-2011. |
Carl's latest REBOL blog is dated 28-Mar-2011: http://www.rebol.com/cgi-bin/blog.r | |
So seem to be 1 month 2 weeks since last REBOL blip. | |
older newer | first last |