The hook
'see?' ]# 1 2 3 4
4
works fine...
greg
~krsnadas.org
--
from: 'Pascal Jasmin' via Programming <[email protected]>
to: "[email protected]" <[email protected]>
date: 19 May 2014 22:01
subject: Re: [Jprogramming] Understandable J
is that special code? because its not supposed to work ie:
'see?' # 1 2 3 4
|domain error
The above (] +/ % #) is even a special parsing rule?
>At any rate, the conventions I use help the one who will read my code the
>most, but I'd still recommend to anyone to avoid long hooks.
--
From: Raul Miller <[email protected]>
To: Programming forum <[email protected]>
Cc:
Sent: Monday, May 19, 2014 11:38:24 PM
Subject: Re: [Jprogramming] Understandable J
That's an interesting line of thought.
>Note that we can take a fork and ensure that we always use its monadic
>definition by prefixing it with the verb ]
Here's a mean example:
mean=: ] +/ % #
mean 2 3 5 7
4.25
'see?' mean 2 3 5 7
4.25
>Now obviously there isn't a lot of need for this kind of thing - we've gone
>for years (decades?) without anyone complaining about its absence. But it's
>still kind of neat.
Thanks,
Raul
--
from: 'Pascal Jasmin' via Programming <[email protected]>
to: "[email protected]" <[email protected]>
date: 19 May 2014 20:19
subject: Re: [Jprogramming] Understandable J
Here are some ways to improve readability for me:
lets take,
quicksort=: (($:@(<#[),(=#[),$:@(>#[))({~ ?@#))^:(1<#)
the first step is spacing out the train:
quicksort=: (($:@(<#[) , (=#[) , $:@(>#[)) ({~ ?@#)) ^: (1<#)
>the next step is avoiding the hook that takes a while to find due to all the
>parens:
quicksort=: (] ($:@(<#[) , (=#[) , $:@(>#[)) ({~ ?@#)) ^: (1<#)
>I find the above superhelpful because the left ] tells me right away that it
>is a fork. and then automatically all of the references to [ in the pivot verb
>are actually ones to y argument, and I know that the whole verb is monadic.
>optional, but I think still helpful, is to add whitespace to long parens, and
>it doesn't hurt to get rid of right hook:
quicksort=: (] ( $:@(<#[) , (=#[) , $:@(>#[) ) (] {~ ?@#)) ^: (1<#)
--
from: Don Kelly <[email protected]>
to: [email protected]
date: 19 May 2014 18:55
subject: Re: [Jprogramming] Understandable J
>Agreed but both need attention- often the most refined program may be the
>hardest to read.
--
from: 'Bo Jacoby' via Programming <[email protected]>
reply-to: [email protected]
to: "[email protected]" <[email protected]>
date: 17 May 2014 21:31
subject: Re: [Jprogramming] Understandable J
Improve the program rather than the documentation.
--
from: Don Kelly <[email protected]>
to: [email protected]
date: 17 May 2014 19:49
subject: Re: [Jprogramming] Understandable J
>I find that putting code with lots of explanatory NB.'s and maybe a how-to
>paragraph as a noun in a script is essential. This also works for little code
>snippets than may prove useful in the future (and sometimes with variations
>listed). Examples also help.
>This is not only an aid to me, but to others who may use the code. This came
>from past APL experience where I would look at something I wrote and wondered
>what I did. Starting from scratch is nice but if the hard work has been done,
>why do it again
except to improve on the approach?
There are 2 ways:
>1)intersperse comments within multiline verbs to help interpretation of the
>line
>2)provide a noun such as "howN' and example of this is the following
>definition from an Essay on Newton Raphson where the following is given
N=: 1 : '- u % u d. 1' (which could be given a better name)
>this could be followed by a series of NB.'s in the script indicating the usage
NB. (_2+*:)N ^:c]xo solves x^2 =2 using c iterations starting form a guess xo
or with more Nb. for more detail.
--
from: robert therriault <[email protected]>
to: [email protected]
date: 15 May 2014 23:36
subject: Re: [Jprogramming] Understandable J
Thanks Raul,
>I am happy with some of the progress that I am making in my projects (and
>occasionally programming as well), but I like the poetry of J and in that way
>part of the challenge is placing the context through the examples. Without
>that context a poem is just pretty words on a page and a tacit expression
>without examples may not even reveal its valence.
>I think that there are opportunities in combining good test driven development
>with the rapid prototyping abilities of J -- but first I am playing with J
>Labs as a medium of expression, education, art etc.
Cheers, bob
>ps. I appreciate the support for my work. The fact that I am a terrible
>programmer does not keep me from making terrible programs that explore neat
>ideas. Life's too short to let a lack of talent hold you back :-)
--
from: Raul Miller <[email protected]>
to: Programming forum <[email protected]>
date: 15 May 2014 23:10
subject: Re: [Jprogramming] Understandable J
>I would not knock "starting from scratch" as a bad thing. Arthur Whitney has
>been known to do that, for example.
>I think it matters more what you are accomplishing and your ability to make
>that useful for other people.
Thanks,
--
from: robert therriault <[email protected]>
to: [email protected]
date: 15 May 2014 23:07
subject: Re: [Jprogramming] Understandable J
>I am a terrible programmer, but I have found that including comments that have
>examples of what the entity should do, are usually enough for me to figure out
>what is going on.
>Without that ... I usually start from scratch, as that is faster and less
>frustrating.
I really am terrible at programming.
Cheers, bob
--
from: 'Bo Jacoby' via Programming <[email protected]>
to: "[email protected]" <[email protected]>
date: 15 May 2014 22:52
subject: Re: [Jprogramming] Understandable J
>"how does one write understandable J?" One does not write understandable J!
>One writes as compactly as possible, and if it needs to be understood it's
>parts are investigated piece by piece. Understandability is not a property of
>text, but rather a property of relationship between text and reader. / Bo.
--
from: Don Guinn <[email protected]>
to: Programming forum <[email protected]>
date: 15 May 2014 18:50
subject: Re: [Jprogramming] Understandable J
>What is easy and obvious depends so much on one's background. Several years
>ago we tried to teach a woman, at the time in her 80's, how to use a Windows
>computer. Total failure. The real problem was that she could see no use in or
>reason to use a computer. She had no interest in learning it.
>Anyone who thinks that today's computer technology is intuitive, obvious and
>easy should go to an old folk's home and try to teach them to use a smart
>phone. But for a four-year-old. Piece of cake.
--
from: Raul Miller <[email protected]>
to: Programming forum <[email protected]>
date: 15 May 2014 17:10
subject: Re: [Jprogramming] Understandable J
>I am convinced that most code is not understandable to most people, regardless
>of the language it is written in. When I look at how the computer industry has
>progressed, I see this more and more. People write huge amounts of code, don't
>document it very well, then other people use arbitrary bits of it and things
>sort of just freeze at that point.
>Personally, also, when I read code in any language, I do not feel I really
>understand it until I see what it does to representative data.
>So clear descriptions, simple data, and good labels are where I would focus
>most of my efforts in making code readable. And I would also expect that most
>of my code is going to be unread by most people (and I'll get dinged for
>utterly random stuff by people who do read it).
>I think the point of readability is: you are going to need to be able to fix
>it, yourself, when it breaks, so you need to make it readable for yourself.
>And for that purpose, coming back and trying to read it a month or so after
>you've written it can be a good exercise.
>Also, I've found that documenting code is a great way of making code simpler.
>It's quite often the case that it's easier to change the code to be easy to
>document than it is to document some coding quirks that originally seemed to
>be a good idea. So if you want readable code, another good thing to do is have
>a technical writer (or at least someone reasonably literate) work with the
>programmer to document it for some audience.
>Of course, the most important thing is making sure that it works.
Thanks,
--
from: Kip Murray <[email protected]>
to: "[email protected]" <[email protected]>
date: 15 May 2014 14:23
subject: [Jprogramming] Understandable J
>How does one write understandable J? I offer my newt adverb below which uses
>spaces to promote understandability.
>Another technique might be Linda's "bottom up" style of first showing pieces
>then putting the pieces together. What are your techniques? Please
>illustrate.
>We would like at least to understand our own code when we come back to it!
NB. Newton's method
newt =: 1 : 0
t =. y
h =. 1 % 512
whilst. t ~: s do.
s =. t
t =. s - +: h * (u s) % (u s + h) - u s - h
h =. h % 2
end.
t
)
(2 - *:) newt 2 NB. Find root of 2 - *: near 2
1.41421
(2 - *:) newt _2 NB. Find a root near _2
_1.41421
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