I have added to http://code.jsoftware.com/wiki/Vocabulary/cor
especially notes 1, 2, and 12 and new example 27 at the end. See if this would have helped.
Henry Rich On 2/12/2016 2:03 PM, Matthew Baulch wrote:
Ok. That explains things well. So the the line(s) containing : behave just as if : is an everyday conjunction. It's the lines AFTER : that are treated specially. I suppose that's quite a clear design. I'll re-read the documentation. Like you say, once I know what's going on, these subtle points are more likely to stand out. ". does indeed have unlimited potential—over the domain of character arrays anyway. I'm trying to wrap this construction in a verb so I can obtain these multi-line definitions without explicitly calling ". . Just for feelings of purity. It doesn't seem like this can be accomplished tacitly. I'm starting to think that 0:0 has to appear in each definition, and so defining such a verb may not be possible. Oh well. Thanks. : makes sense now. On 12 Feb 2016 2:11 pm, "Henry Rich" <[email protected]> wrote:Forgive me if I'm wrong, but I don't see a discussion of 'expressions totheright of zero' (such as '-.LF' in '0 : 0 -. LF') in either of your links.No. But that isn't surprising when you understand what's going on. 0 : 0 creates a noun. Because conjunctions are executed before verbs, 0 : 0 -. LF is the same as (0 : 0) -. LF (0 : 0) creates a noun that can be used just as any other noun is used. You can add to it, subtract from it, execute it... The (-. LF) has nothing to do with the execution of (:). What I'm saying is, if you are OK with something like ".;._2 (0 : 0) [which feeds the result of (0 : 0) into a verb], you should ipso facto be OK with (0 : 0) -. LF which also feeds that result into a verb, just from the left this time. The (:) in (0 : 0) is executed WHEN (:) IS EXECUTED, i. e. at the appropriate time during the parse [see NuVoc for explanations]. After (:) has read its fill, execution of the sentence continues. So, you can have (0 : 0) ,&(".;._2) (0 : 0) 1 2 3 ) 10 20 30 40 50 60 70 80 90 ) 10 20 30 40 50 60 70 80 90 1 2 3 Two (0 : 0) in one sentence [the parentheses are not required]! and executed right-to-left. (".) has unlimited potential, but often is put to mundane use. When I was starting with J I felt a frisson of daring when I used it, but now it's just another verb to me. Henry RichI'd welcome any correction. Cheers. It's pretty well explained at http://code.jsoftware.com/wiki/Vocabulary/NounExplicitDefinition The question is, How would you know to read that? Suggestions welcomed. When you say "expression following the 0", I'm not sure which 0 you mean. : is the all-purpose entity creator; the left 0 says 'create a noun', and the right 0 says 'make that noun from the upcoming lines of input'. Full details are spelled out in several pages starting at http://code.jsoftware.com/wiki/Vocabulary/cor Henry Rich On 2/11/2016 12:55 AM, Matthew Baulch wrote: Thanks everyone. This (let's say) creative use of 0 : 0 makes sense to menow. I wonder if it's an accidental consequence of the implementation that allows an expression following the 0, or whether it's a deliberate design decision. Either way, it makes sense to have it documented. Can't see it in NuVoc or the Dictionary. Of course, I may have overlooked it. Honestly, to obtain something simple like multi-line noun definitions, ". does seem like quite a heavy-handed tool. It does work however, so I probably shouldn't grumble. Cheers. On Wed, Feb 10, 2016 at 10:29 PM, Matthew Baulch <[email protected]> wrote: Looking at this more closely now. I'm a bit puzzled about the use of -.here. Obviously this is used here in dyadic form. In x -. LF the LF characters are, of course, removed from x. What is the x here? I have seen that it works--not doubting that. Just trying to work out how. Sorry. There's probably something obvious I've missed. On Wed, Feb 10, 2016 at 12:52 AM, Raul Miller <[email protected]> wrote: If you do not have good names for partial calculations, that might bea sign that you need to think a bit more about the abstractions you are using. It can be difficult for other people to read if you don't make sufficient effort to label your abstractions. Also, I would note that your 'c0' is not a combinator, as you are not using its dyadic definition. So you might want to use a different name for that one. Perhaps: v0=:c0 That said, if you really want to execute really long lines, you can do that using ". 0 :0-.LF and indented text. (You need the indentation because line feeds will not separate words here.) For example: myStruct=: ". 0 :0-.LF v0 p0 c1 p1 c2 p2 c3 p3 c4 p4 c5 p5 c6 p6 c7 p7 c8 p8 c9 p9 c10 p10 c11 p11 c12 p12 c13 p13 c14 p14 c15 p15 c16 p16 c17 p17 c18 p18 c19 p19 c20 p20 c21 p21 c22 p22 c23 p23 c24 p24 c25 p25 c26 p26 c27 p27 c28 p28 c29 p29 c30 p30 ) I hope this helps, -- Raul On Tue, Feb 9, 2016 at 4:59 AM, Matthew Baulch <[email protected]> wrote: Suppose I wish to construct a complex, non-regular deeply nestedstructure:to model some inherently non-linear system. A natural approach (for me,anyhow) is to construct a library of combinators, or a domain specific language, with which to specify the (boxed) structure. J rises easily to the task, and before long I'm looking at long function trains of the form myStruct =: c0 p0 c1 p1 c2 p2 ... cN pN where the ci are (combinator) verbs, and the pj are (parameter) nouns. Nice. Easy. Only trouble is, N may be large and J prefers such statements to sit on asingle line. Correct? I can split my definition:msPartA =. ..... msPartB =. ..... ..... msPartX =. ..... myStruct =: msPartA msPartB .... msPartX though this feels awkward. The most obvious issue is that the PartA, ...,PartX are distracting; unless of course I can find a natural way ofsplitting and naming them. Ideally, the parts should be as close to a comfortable line width as possible. Again, awkward. If myStruct1 and myStruct2 have the same partitioning scheme but myStruct2 (for instance) ismuch larger than myStruct1, there will be many sparsely, or manyoverpopulated lines. Awkward too. I love J. It handles complex regular data so elegantly. How can I bring similar elegance to irregular data? Can my combinators be rescued, or should I use another approach? ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm ----------------------------------------------------------------------For information about J forums see http://www.jsoftware.com/forums.htm ----------------------------------------------------------------------For information about J forums see http://www.jsoftware.com/forums.htm ----------------------------------------------------------------------For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
