Pascal, the definitions were provided, after the countdown, in my first
post. However, as I mentioned in that post these are hints/solutions
because I was using a version of J with extensions described in [1] (referred
in the same post) and it is not yet widely available but we are planning to
release the patches and a new 32-bit Windows version probably this week. I
also gave some hints in that post on how to write them using an official
version but it is not straightforward exercise.
On Tue, Mar 4, 2014 at 7:50 AM, Pascal Jasmin <godspiral2...@yahoo.ca>wrote:
> thank you Dan and Pepe,
>
> I've been unable to track down the definitions used below. Though I think
> I remember seeing them recently... just not recently enough.
>
>
> ________________________________
> From: Dan Bron <j...@bron.us>
> To: programm...@jsoftware.com
> Sent: Monday, March 3, 2014 8:56:50 PM
> Subject: Re: [Jprogramming] Tacit recursion without $:
>
>
> Pepe wrote:
> > The problem is, as you now know, exceeding the 100 KB limit. So I
> > followed Chris' advice and trimmed the old messages.
> >
> > These are the answers to your questions,
>
> Below is the message Pepe is responding to, for context (and so that it
> shows up in the Forum archives, which I rely on).
>
> Pepe wrote (earlier):
> > Dan, in the meantime you might find the following somewhat enticing,
> >
> > u0`u1`u2`u3 At=. (at~&:train)/ o |. f.adv
> > u0@:u1@:u2@:u3
> >
> > or even better (removing the middle man),
> >
> > eval=. train o ({: ; (an o }:)) NB. Verb form
> > ...
> > [: u0 u1 u2 u3 At
> > u0@:u1@:u2@:u3
>
> Awesome! I've wanted something like this (no-middle-man) since 2010 [1],
> and the J community has been wanting (train-to-pipeline) since at least
> 2003 [2]. I'm very glad to have these tools and they're going straight in
> my toolbox. Thank you.
>
> I think the only last thing we need is some nicer notation for the pattern.
> In [2], Paul Chapman proposed defining (: ): for this purpose, and that
> idea has been raised a few times since (mostly by me :). But, rather than
> change the DoJ so drastically, with the advent of Unicode we should be
> able to provide, in userspace, our own custom symbols to denote a verb
> pipeline (perhaps guillemets e.g., <<u1 u2 u3 u4>> as I suggested in [1],
> but really, anything from [4] could work). Of course, that would require
> us to add support for Unicode identifiers in the language, so I'm glad to
> see active discussion of that idea in recent threads (it would be more
> satisfying and less risky to change the language to support Unicode than
> introduce new punctuation like (:): or (.). etc.)
>
> [These are the questions Pepe was responding to, below]
>
> I haven't had a chance to try out your examples below yet, but did you
> manage to work around the rightmost-hook limitations that have plagued all
> tools in this vein to date [3]? What does your utility produce for (u1 u2
> (u3 u4)) ?
>
> Does it preserve the embedded hook at the right edge, or glue its
> components together with the top-level verbs? Is that consistent with its
> treatment of other nested trains (e.g. a hook embedded somewhere off the
> right edge, or nested forks, etc)? What does it do with doubly-nested
> trains, and deeper?
>
> If it doesn't produce u1@:u2@:(u3 u4) for u1 u2 (u3 u4), I have a vague
> sense that this problem arose in another context quite recently, and
> someone posted a solution. Maybe Raul and/ or Pascal?
>
> -Dan
>
> [1] Adverb for creating verb pipelines from trains,
> which I couldn't get working the way I wanted:
>
> http://www.jsoftware.com/pipermail/programming/2010-June/019756.html
>
> [2] Paul Chapman on using '):' to enclose trains and glue the component
> verbs together using @:, in order to reduce visual noise in J
> expressions (because pipelines are a common pattern and having lots
> of @: clutters them up & buries the logic):
>
> http://www.jsoftware.com/pipermail/general/2003-August/015037.html
>
> [3] Paul's script to produce pipelines from trains:
> http://www.jsoftware.com/pipermail/general/2003-August/015037.html
>
> [4] Various ways of denoting quotation, e.g.?u1 u2 u3 u4:
>
> http://en.m.wikipedia.org/wiki/International_variation_in_quotation_marks
>
> [Chronologically, the message below appeared before this one, but
> sequentially it comes after]
>
> ----- Original Message ---------------
>
>
> Subject: Re: [Jprogramming] Tacit recursion without $:
> From: Jose Mario Quintana <jose.mario.quint...@gmail.com>
> Date: Mon, 3 Mar 2014 12:13:35 -0500
> To: Programming forum <programm...@jsoftware.com>
>
> Dan,
>
> The problem is, as you now know, exceeding the 100 KB limit. So I
> followed Chris' advice and trimmed the old messages.
>
> These are the answers to your questions,
>
> [: u0 u1 At
> u0@:u1
>
> I should point out that neither there is a train nor a need for
> parentheses. There is an issue when there is a single verb in the strand
> (because a verb associated to / is not executed when the argument is a
> single item),
>
> [: u0 At
> +--+
> |u0|
> +--+
>
> It can be fixed as follows but I might not be worth it,
> At=. (train ^: (L.~: 0:)) o ((at~&:train)/) o |. f. sv
> [: u0 At
> |value error: u0
> [: * At
> *
> It also produces an error for an empty strand but this behavior seems right
> to me,
> [: At
> |domain error: At
> | @:a:
>
> Regarding (u1 (u2 u3)) , (u1 u2 (u3 u4)),
>
>
> [: u1 (u2 u3) At
> u1@:(u2 u3)
>
> [: u1 u2 (u3 u4) At
> u1@:u2@:(u3 u4)
>
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