Another way to achieve controled polymorphism
is to declare several overrides for the same
J verb:
NB.@ int add(int a, int b)
NB.@ int add(double a, double b)
NB.@ int add(int[] a, int[] b)
add=: 3 : 0
'a b'=: y
a + b
)
Such form is applicable to internal libraries,
but is not used for external business interfaces
such as Web Services.
--- Oleg Kobchenko <[EMAIL PROTECTED]> wrote:
> No, it gives the freedom of controling the
> strictness to the developer.
>
> In some situations, strictness is preferred as
> it gives compile-time error prevention, declarative
> operation intention, etc.
>
> For a broader, open-ended, polymorphics uses, the
> declaration can always be loosened. But the conventions
> of C# or Java still need to apply.
>
> int sum(int[] a); // a strict array
> sum(new int[]{1,2,3,4});
>
> int sum(object[] a); // a loose array
> sum(new object[]{1,2,3.14,4.56,5.67});
>
> int sum(object a); // any object(s)
> sum(new int[][]{{1,2},{3,4}});
>
>
> --- Devon McCormick <[EMAIL PROTECTED]> wrote:
>
> > Does this restrict use of J's strengths such as loose typing of different
> > numeric types and automatic extension to arrays? For instance, could I
> > define a single "sum" method that would work when used in the following
> > ways?
> >
> > sum(1,2,3,4)
> > sum(1,2,3.14,4.56,5.67)
> > sum([table of numbers])
> >
> >
> > On 3/5/08, dly <[EMAIL PROTECTED]> wrote:
> > >
> > > Oleg - this solution fits right in to .NET and would probably lead to
> > > increased use of J!
> > >
> > > Donna
> > > [EMAIL PROTECTED]
> > >
> > >
> > >
> > >
> > >
> > > On 5-Mar-08, at 5:30 PM, Oleg Kobchenko wrote:
> > >
> > > > This is really interesting how managed to embed
> > > > J session into a .NET desktop application.
> > > >
> > > > Regarding calling J from .NET code, what I meant
> > > > that, in particular since people can be put off
> > > > by J code, it could even be more upsetting when
> > > > it is intermingled with C# code, even if it is
> > > > constructing simple expressions and calls to J verbs
> > > > defined in script.
> > > >
> > > > I think that it would cleaner if a calling convention
> > > > is established, so that from C# it looks almost like
> > > > calling another C# library.
> > > >
> > > > One way to achieve this is how Web Services are built--
> > > > with the use of generated artifacts. You start with a
> > > > separate J script file with certain syntax conventions
> > > > for top-level verbs; then you write a few verbs and
> > > > run the generator; it will produce the C# wrapper class
> > > > with those verbs as public methods; it is referenced and
> > > > imported into C# program; then simply instanciated and
> > > > called as any C# class.
> > > >
> > > > The syntax convention can even support multiple even
> > > > typed parameters. For example,
> > > >
> > > > NB.@ int add(int a, int b)
> > > > add=: 3 : 0
> > > > 'a b'=: y
> > > > a + b
> > > > )
> > > >
> > > > which in the generated artifact wrapper class will become
> > > >
> > > > class MyJLib {
> > > > JClass _j = new JClass();
> > > > ...
> > > > public MyJLib() {
> > > > _j.Do("load '~user/myj/myjlib.ijs'");
> > > > }
> > > > ...
> > > > public int add(int a, int b) {
> > > > _j.Set("a",a);
> > > > _j.Set("b",b);
> > > > _j.Do("z=: add a;b",b);
> > > > return _j.Get("z");
> > > > }
> > > > ...
> > > > }
> > > >
> > > > Now it is used simply:
> > > >
> > > > MyJLib jl = new MyJLib();
> > > >
> > > > int c = jl.add(11,22);
> > > >
> > > >
> > > > Note that such approach can easily generate other
> > > > interfaces: Web Services, Java beans, etc.
> > > >
> > > >
> > > > --- Alex Rufon <[EMAIL PROTECTED]> wrote:
> > > >
> > > >> Hello Oleg,
> > > >>
> > > >> Thanks for the links. Your examples are actually better and I'll
> > > >> use them on Saturday.
> > > >>
> > > >> In the last part of your email, you mention something about
> > > >> letting the developers feel the
> > > >> awesome power of interactive execution of a J Session.
> > > >> Unfortunately, the J session window
> > > >> "scares" them and the "cryptic" way of getting data from a
> > > >> database actually puts them off. So I
> > > >> created an application called SmartEOE.IDE. I did it partly as a
> > > >> solution to the problem and to
> > > >> actually build a true Model-Viewer-Controller application in C#.
> > > >> The idea is that the developers
> > > >> have a tree window for each Library->J Script and an editor window
> > > >> for the actual scripts. They
> > > >> can then run and test the script in the embedded J window at the
> > > >> same time it allows them to
> > > >> retrieve data from familiar data sources and be able to send it to
> > > >> the J session. I took some
> > > >> screenshots and uploaded them to my website in:
> > > >> http://amrufon.spaces.live.com/photos/cns!2B169BDA829381E6!194/
> > > >>
> > > >> I will be emphasizing that before they embed their J scripts into
> > > >> their C# code, they can test
> > > >> it out with "real" data in the IDE. So when they are happy, they
> > > >> can then proceed and update
> > > >> their C# code with the J script, compile then deploy.
> > > >>
> > > >> Of course, I will still show them that there is an option where
> > > >> they can encapsulate all of the
> > > >> code that uses J so that it becomes a black box library. Still, my
> > > >> intention right now is to get
> > > >> them interested to use in-line J scripts and then later on convert
> > > >> C# modules into J verbs
> > > >> leaving the C# function as a wrapper method.
> > > >>
> > > >> Again ... thanks. :)
> > > >>
> > > >> r/Alex
> > > >>
> > > >> -----Original Message-----
> > > >> From: [EMAIL PROTECTED] [mailto:chat-
> > > >> [EMAIL PROTECTED] On Behalf Of Oleg Kobchenko
> > > >> Sent: Tuesday, March 04, 2008 7:28 PM
> > > >> To: Chat forum
> > > >> Subject: RE: [Jchat] Re: the purity of quantified conception
> > > >>
> > > >> You should be prepaired that developers may not be as
> > > >> technically naive as their technical managers.
> > > >>
> > > >> http://www.csharp-station.com/HowTo/StringJoinSplit.aspx
> > > >>
> > > >> So starting with this example you should admit that
> > > >> it was simple enough so that the managers would get it
> > > >> and be lured to get you guys here, but now we gonna
> > > >> talk about some real cool stuff.
> > > >>
> > > >> .NET has vast standard libraries that handles numerous
> > > >> stock operations on simple objects like strings and collections.
> > > >> Whereas the forte of J is a few really powerful operations
> > > >> which generalize over higher-order structures in compact
> > > >> yet expressive notation(*).
> > > >>
> > > >> To expand on the Join example, you can show how to turn
> > > >> a matrix into HTML table in a one-liner.
> > > >>
> > > >> A second example of the .NET/J distinction can be that
> > > >> J has no dedicated operation for SubStr found in mostly
> > > >> any language library. However is can be easily done with
> > > >> Cut <;.0 and easily generalized to simultaneous multiple
> > > >> substrings in a one-liner and to a sub-matrix etc.
> > > >> Related examples here are running average (infix) and matrix
> > > >> convolution with <;.3 (another cut).
> > > >>
> > > >> Of course C# developers are really excited about Linq. So you
> > > >> must show Linq as they've never seen before, the way
> > > >> it is done in J
> > > >>
> > > >> http://www.jsoftware.com/jwiki/DB/Flwor
> > > >>
> > > >> (*) J notation best preserves its clarity when maintained
> > > >> separately from the client calling code, so its best not
> > > >> intermingle C# and J code, but keep a thin calling layer
> > > >> with clean separate C# and J sources. To this end,
> > > >> it is helpful to organize J code with externally callable
> > > >> entry points (top-level verbs) and some kind of convention.
> > > >> It is the same with SQL. Also keeping it separate makes
> > > >> use of the full power of J session for trial-and-error
> > > >> experimentation--another advantage of interpretive environment
> > > >> worth showing off.
> > > >>
> > > >>
> > > >> --- Alex Rufon <[EMAIL PROTECTED]> wrote:
> > > >>
> > > >>> The WAN is down so I can't work ... then I accidentally click on
> > > >>> this email.
> > > >>>
> > > >>> I am basically the ONLY J programmer in our office. Were
> > > >>> basically a C# and VB.NET software
> > > >>> house but our core processing is done in J. Unfortunately, I am
> > > >>> the only J programmer (I can
> > > >>> repeat that as a mantra you know).
> > > >>>
> > > >>> For the longest time (going 8 years now), I've been trying to
> > > >>> convince other teams to adopt J
> > > >>> into their project ... and quite frankly I continue to fail.
> > > >>>
> > > >>> You said:
> > > >>> " People don't embrace J because, having been exposed to its awe-
> > > >>> inspiring qualities, they are
> > > >>> swept away by "the purity of quantified conception." That is
> > > >>> likely to be a factor, but
> > > >> without
> > > >>> a sense that J provides what they need in their actual context
> > > >>> they'll never go beyond initial
> > > >>> dabbling."
> > > >>>
> > > >>> Is VERY-VERY true.
> > > >>>
> > > >>> Last Saturday, I did another presentation to the Technical
> > > >>> Managers trying to convince them to
> > > >>> adopt J. But this time, I tried another approach (read this as
> > > >>> being sneaky). Instead of doing
> > > >>> examples on how it works, what the language is about and its
> > > >>> capabilities. I showed them how I
> > > >>> use C# with J to do the following:
> > > >>> 1. Array processing
> > > >>> 2. File processing
> > > >>> 3. Converting MS-SQL DataSet to SQL INSERT statements
> > > >>>
> > > >>> For the array processing, one of my example is creating the classic:
> > > >>> Select * from FRUITS where NAME in ('Orange','Apple','Banana')
> > > >>>
> > > >>> Normally, to do this in C#, they would have
> > > >>> string[] data = {"Orange","Apple","Banana"};
> > > >>>
> > > >>> What they actually need is to have the data in this format:
> > > >>> 'Orange','Apple','Banana'
> > > >>>
> > > >>> To do this in C# they have to loop through each of the item in
> > > >>> the array like so:
> > > >>> string result = "";
> > > >>> for (int i = 0; i < data.length; i++)
> > > >>> {
> > > >>> result += "'" + data[i].tostring() + "',";
> > > >>> }
> > > >>> // We have to remove the ending "," comma
> > > >>> if (result.length > 0)
> > > >>> {
> > > >>> result = result.trim(result.length - 1,1);
> > > >>> }
> > > >>>
> > > >>> Where if they use J, all they need to do is:
> > > >>> JSession objSession = new JSession();
> > > >>> string[] data = {"Orange","Apple","Banana"};
> > > >>> string result;
> > > >>> // Send the data to EOE
> > > >>> objSession.Variable("Temp1",(object)data);
> > > >>> // Process the data
> > > >>> objSession.Eval("res=: ',' charsep '''' ,~ each '''' with each
> > > >>> Temp1");
> > > >>> // this can even be shortened with
> > > >>> // objSession.Eval("res=: datasep Temp1");
> > > >>> // Get the data back to C#
> > > >>> result= (string)objSession.Variable("res");
> > > >>> // SQL command
> > > >>> string sqlCommand = "Select * from FRUITS where NAME in (" +
> > > >>> result + ")";
> > > >>>
> > > >>> And the other thing I pointed out is that in the original C#
> > > >>> code, they have to do this:
> > > >>> // We have to remove the ending "," comma
> > > >>> if (result.length > 0)
> > > >>> {
> > > >>> result = result.trim(result.length - 1,1);
> > > >>> }
> > > >>>
> > > >>> By putting things into the perspective of what they need now, I
> > > >>> may have some measure of
> > > >>> success. A few of the Technical Managers want to do another
> > > >>> session on Saturday but this time
> > > >>> they will be bringing their developers and wants a more detailed
> > > >>> discussion on the language.
> > > >> The
> > > >>> warehousing team is actually scheduling a meeting when I get back
> > > >>> to the Philippines for me to
> > > >>> help with their developers on data processing.
> > > >>>
> > > >>> I hope that this continues and I can encourage more people to
> > > >>> adopt the language. :)
> > > >>>
> > > >>> r/Alex
> > > >>>
> > > >>>
> > > >>> -----Original Message-----
> > > >>> From: [EMAIL PROTECTED] [mailto:chat-
> > > >>> [EMAIL PROTECTED] On Behalf Of Tracy Harms
> > > >>> Sent: Friday, January 25, 2008 4:17 AM
> > > >>> To: [email protected]
> > > >>> Subject: [Jchat] Re: the purity of quantified conception
> > > >>>
> > > >>> Randy MacDonald wrote:
> > > >>>
> > > >>>> Happy New Year, Tracy;
> > > >>>
> > > >>> A belated Happy New Year to you, too, Randy.
> > > >>>
> > > >>>>
> > > >>>> My personal thought about that "law" that says all systems of
> > > >>>> sufficient complexity are equivalent to lisp, my thought is,
> > > >>>> that all matter of sufficient temperature becomes plasma. True,
> > > >>>> but not of much use in the ordinary world.
> > > >>>
> > > >>> I had not recognized the allusion to that saying, so thanks for
> > > >>> pointing it out.
> > > >>>
> > > >>>> BTW, did the xkcd post have such an effect on the lisp community?
> > > >>>
> > >
> > > >>> Touch�
> > >
> > > >>>
> > > >>> Perhaps there is a fine line between desiring to see the beauty
> > > >>> of J more widely recognized,
> > > >> and
> > > >>> falling into factional squabbling. Lisp has had a small but
> > > >>> fervent user base for a long time,
> > > >>> and XKCD is one manifestation of that. At the point I start
> > > >>> letting myself think "if they only
> > > >>> knew..." I've fallen off the edge into fantasy.
> > > >>>
> > > >>> People don't embrace J because, having been exposed to its awe-
> > > >>> inspiring qualities, they are
> > > >>> swept away by "the purity of quantified conception." That is
> > > >>> likely to be a factor, but
> > > >> without
> > > >>> a sense that J provides what they need in their actual context
> > > >>> they'll never go beyond initial
> > > >>> dabbling.
> > > >>>
> > > >>> --
> > > >>> Tracy
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > ______________________________________________________________________
> > > > ______________
> > > > Be a better friend, newshound, and
> > > > know-it-all with Yahoo! Mobile. Try it now. http://
> > > > mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ
> > > >
> > > > ----------------------------------------------------------------------
> > > > For information about J forums see http://www.jsoftware.com/forums.htm
> > >
> > > ----------------------------------------------------------------------
> > > For information about J forums see http://www.jsoftware.com/forums.htm
> > >
> >
> >
> >
> > --
> > Devon McCormick, CFA
> > ^me^ at acm.
> > org is my
> > preferred e-mail
> > > ----------------------------------------------------------------------
> > For information about J forums see http://www.jsoftware.com/forums.htm
>
>
>
>
> ____________________________________________________________________________________
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