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 me
now. 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 be
a 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 nested
structure:
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
a
single 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 of
splitting 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) is
much larger than myStruct1, there will be many sparsely, or many
overpopulated 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?
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