World: r3wp
[Core] Discuss core issues
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ChristianE 12-May-2011 [1394] | That shouldn't be a problem, Max, I don't think too many people abuse implementation specific hacks like this one in code other than zen examples ... ;-) |
Sunanda 13-May-2011 [1395] | Long discussion of R3/local here: http://www.rebol.net/cgi-bin/r3blog.r?view=0341 |
Geomol 13-May-2011 [1396] | Tonight's Moment of REBOL Zen: >> skip [a b c] to integer! true == [b c] >> skip [a b c] true == [a b c] |
BrianH 13-May-2011 [1397x2] | Yup. The order of logic values as considered by SKIP, PICK and POKE is true then false. This was done to make PICK compatible with EITHER. |
Carl uses PICK instead of EITHER a lot. He also marvels that this trick isn't used more often, especially since he added logic indexing specifically for that purpose :) | |
Geomol 13-May-2011 [1399] | Interesting explanation! Gives us even more Zen to think about: >> pick [a b] true == a >> pick [a b] to integer! true == a >> pick [a b] false == b >> pick [a b] to integer! false == none |
Maxim 13-May-2011 [1400] | well, difference in types is expected, its the point of having dynamic typing. I don't think its a required feature for type casting to result in symmetric uses of other functions. I expect to-from one type to another to be as symmetric as possible, but not what they mean in another context of usage. |
BrianH 13-May-2011 [1401] | Yup, because PICK, POKE, AT, INDEX? and /1 work with indexes, while SKIP works with offsets. |
Henrik 13-May-2011 [1402] | I would like to use the PICK option more, if also NONE was supported as the first item. |
BrianH 13-May-2011 [1403x2] | But that would make PICK data none the same as PICK data true, not PICK data false. |
I would really like it if TRUE? was native. There's too much code that needs PICK reversed-data NOT condition, which would be better expressed as PICK data TRUE? condition. | |
Henrik 13-May-2011 [1405] | perhaps there should be a three-state PICK instead. |
BrianH 13-May-2011 [1406x2] | 0 = none, 1 = true, 2 = false? |
Or -1, 0, 1 if you are thinking in terms of offsets instead of indexes. | |
Henrik 13-May-2011 [1408] | that depends if both the concept of three states and index direction change can be merged into one function and if that makes sense. |
BrianH 13-May-2011 [1409x5] | I like that PICK is stopping point for none propagation. PICK data none should trigger an error, because otherwise you couldn't tell the difference between that and PICK [#[none]] 1. |
is -> is a | |
We keep adding more points of none propagation, and every time we add one it makes more errors propagate further away from their point of origin. This makes it harder to figure out which code caused the error where none wasn't screened for or checked for, making it that much more difficult to debug. | |
We don't want REBOL code to be as difficult to debug as SQL. | |
Although PICK does propagate none indexes for datatypes where PICK acts the same as SELECT, such as map! or object!. | |
Geomol 14-May-2011 [1414] | Tonight's Moment of REBOL Zen: Literal and Get Arguments in R2 see: http://www.rebol.com/docs/core23/rebolcore-9.html#section-3.2 These functions use Literal Arguments: ++ -- ? ?? cd default deflag-face first+ flag-face flag-face? for forall foreach forskip help l ls map-each remove-each repeat secure set-font set-para source This function uses Get Argument: quote It could be questioned, why functions like get set unset in catch throw checksum , which all have arguments named WORD, don't use Literal Arguments? |
BrianH 14-May-2011 [1415x3] | Lit-word arguments are for functions that treat words as keywords or part of the syntax, or for interactive command line functions that are supposed to act like shell funcs. If you use lit-word arguments, you can't easily generate the value passed using an expression, especially in R2 - in R3, those expressions can be put in parens, as is emulated in the R2 mezzanine backports of R3 functions that take lit-word arguments. For instance, if you made GET take a lit-word argument, GET IN wouldn't work. |
The only exception to the above is ++ and --, which take lit-word arguments because their primary use is with a literal word value, so taking a lit-word argument gets rid of a ' in the most common case. And since ++ and -- started in R3 and has its behavior explicitly emulated in R2, you can put word-generating expressions in parens for the less common case. | |
FIRST+ is part of the same exception as ++ and --. | |
GrahamC 14-May-2011 [1418] | Does it make sense to have a timestamp datatype as distinct from a date type |
BrianH 14-May-2011 [1419] | Breakdown by reason: - The word is pseudo-syntax for loop vars: FOR FORALL FOREACH FORSKIP MAP-EACH REMOVE-EACH REPEAT - The function is pseudo-syntax for modifying operations on literal words as variables: ++ -- DEFAULT FIRST+ - Keyword arguments that aren't generally in expressions: DEFLAG-FACE FLAG-FACE FLAG-FACE? SECURE SET-FONT SET-PARA - Interactive shell functions: CD LS ? ?? HELP SOURCE |
GrahamC 14-May-2011 [1420x2] | >> to date! now == 15-May-2011/10:41:51+12:00 >> to date! "15-May-2011" == 15-May-2011 |
to date! creates two different types | |
BrianH 14-May-2011 [1422] | A timestamp more precise than NOW/precise? |
GrahamC 14-May-2011 [1423x5] | No, to date! creates either a date only , or a timestamp at present |
it's inconsistent | |
it should create a date at 0:00 and GMT | |
if those are not provided | |
A source for errors .... | |
BrianH 14-May-2011 [1428] | The date! type is a datetime type with an optional time portion. We can get rid of the time portion already. What do you want that we don't have already? |
GrahamC 14-May-2011 [1429] | to date! should create a timezone and hour by default |
BrianH 14-May-2011 [1430x3] | But that doesn't work when you don't want a time and date. |
>> d: now/date == 14-May-2011 >> d: now d/time: none d == 14-May-2011 | |
When you requested a timestamp type, I thought you were requesting a timestamp type, not a datetime type. | |
GrahamC 14-May-2011 [1433] | in databases .. date and timestamp are different |
BrianH 14-May-2011 [1434] | In some SQL implementations, date, time and datetime are different. And then timestamp is different from all of those. |
GrahamC 14-May-2011 [1435] | maybe just need an explicit to-datetime |
BrianH 14-May-2011 [1436] | A few SQL implementations call the datetime type "timestamp" for some cunfusing reason. It's best to keep the concepts distinct. |
GrahamC 14-May-2011 [1437] | at present 'to-date gives you either a date, or a datetime depending on the input. that is inconsistent |
BrianH 14-May-2011 [1438] | A TO-DATETIME function would be great. GMT by default, or local time like the rest of REBOL? |
GrahamC 14-May-2011 [1439] | localtime would be consistent |
BrianH 14-May-2011 [1440] | In R3, GMT seems to be the default time zone. Interesting. |
GrahamC 14-May-2011 [1441x3] | For many webservices I prefer to work with GMT |
For me the issue is that when dealing with dates, I want to get only the date, but it it's a date with no time portion, then date/date gives you an error. | |
So, I have to check to see what it is first. | |
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