[seqfan] J-language.

[Antti Karttunen]

Douglas McNeil, Simoun Plouffe and Joerg Arndt wrote about the J language
(see below).

No, it's not a joke, but a matrix language based on APL, where the special
function/operator signs of APL has been replaced with the familiar and more
easily remembered ASCII characters. ;-)
And I actually downloaded it just two days ago, for computing a few specific
sequences to OEIS.

Cheers,

Antti Karttunen

On Fri, Jul 2, 2010 at 1:18 AM, <seqfan-request at list.seqfan.eu> wrote:

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> ------------------------------
>
> Message: 10
> Date: Thu, 1 Jul 2010 20:20:25 +0800
> From: Douglas McNeil <mcneil at hku.hk>
> Subject: [seqfan]  most obscure OEIS code ever?
> To: Sequence Fanatics Discussion list <seqfan at list.seqfan.eu>
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>        <AANLkTim53f6Fhm2FDQtYD_9avxhmrXXmaOcpuSBmhRD3 at mail.gmail.com>
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> %o A178683 (J programming language, see http://www.jsoftware.com)
> %o A178683 . aXXXX =: (5 #. ] {::~ [: (i. >./) */&>)@:part"0
> %o A178683 . part =: 3 : 'final (, new)^:y <<i.1 0' NB. Here & below due to
> Hui
> %o A178683 . final=: ; @: (<@-.&0"1&.>) @ > @ {:
> %o A178683 . new =: (-i.)@# <@:(cat&.>) ]
> %o A178683 . cat =: [ ;@:(,.&.>) -@(<.#) {. ]
>
> There are a handful of other sequences with J codes, but this is
> probably the most impressive.  Surprisingly, J appears not to be a
> parody esolang, which was my first guess-- or if it is, the authors
> have admirably moved all-in on the joke and have kept their tongues in
> their cheeks for almost twenty years.  One's tempted to suspect a
> drunken bet gone horribly, horribly wrong..
>
>
> Doug
>
> --
> Department of Earth Sciences
> University of Hong Kong
>
>
>
> ------------------------------
>
>
>
> Message: 13
> Date: Thu, 1 Jul 2010 15:09:56 +0200
> From: Simon Plouffe <simon.plouffe at gmail.com>
> Subject: [seqfan] Re: most obscure OEIS code ever?
> To: Sequence Fanatics Discussion list <seqfan at list.seqfan.eu>
> Message-ID:
>        <AANLkTindomzIu7WOnKhtYH4eJqe4GN37Ar0v1V4ozTCL at mail.gmail.com>
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>
> sorry, but this resembles a kind of joke in smiley language
> more thana real program,
>
> (my own opinion), I don't see the point of
> having sequences coded in that kind of
> cryptic language.
>
> for example for n!, one can give an example
> of a very short C, or whatever language that
> would produce the sequence, that's ok. but
> to have a sequence that has only that is not
> a good idea. ... Some perl programs can be
> made impossible to decode, this is a useless
> exercice.
> we need the name, the ref. something to
> sitck to what is known.
> (end of personal comment).
>
> best regards,
>
> Simon Plouffe
>
>
> ------------------------------
>
> Message: 14
> Date: Thu, 1 Jul 2010 15:46:48 +0200
> From: Joerg Arndt <arndt at jjj.de>
> Subject: [seqfan] Re: most obscure OEIS code ever?
> To: Sequence Fanatics Discussion list <seqfan at list.seqfan.eu>
> Message-ID: <20100701134648.GA12036 at jjj.de>
> Content-Type: text/plain; charset=us-ascii
>
> * Douglas McNeil <mcneil at hku.hk> [Jul 01. 2010 14:55]:
> > %o A178683 (J programming language, see http://www.jsoftware.com)
> > %o A178683 . aXXXX =: (5 #. ] {::~ [: (i. >./) */&>)@:part"0
> > %o A178683 . part =: 3 : 'final (, new)^:y <<i.1 0' NB. Here & below due
> to Hui
> > %o A178683 . final=: ; @: (<@-.&0"1&.>) @ > @ {:
> > %o A178683 . new =: (-i.)@# <@:(cat&.>) ]
> > %o A178683 . cat =: [ ;@:(,.&.>) -@(<.#) {. ]
> >
>
> sendmail.conf on steroids, I am thoroughly impressed.
>
>
> > There are a handful of other sequences with J codes, but this is
> > probably the most impressive.  Surprisingly, J appears not to be a
> > parody esolang, which was my first guess-- or if it is, the authors
> > have admirably moved all-in on the joke and have kept their tongues in
> > their cheeks for almost twenty years.  One's tempted to suspect a
> > drunken bet gone horribly, horribly wrong..
> >
>
> Well, it's a concise language indeed,
> the following (supposedly) computes A005249:
>
>  H=: % @: >: @: (+/~) @: i.
>  det=: -/ .*
>
> Not sure about readability  ;-)
>
> http://en.wikipedia.org/wiki/J_(programming_language)<http://en.wikipedia.org/wiki/J_%28programming_language%29>
> cf. also http://en.wikipedia.org/wiki/Tacit_programming
> " ... or more pithily as pointless programming."
>
> Maybe this really is an in-joke of epic proportions.
>
>
> >  [...]
>
>
>
>