Thanks Henry
po=: 13 :'|:y#:i.*/y'
po2=: 3 :'|:y#:i.*/y'
po
[: |: ] #: [: i. */
po2
3 : '|:y#:i.*/y'
5!:4 <'po'
┌─ [:
├─ |:
──┤ ┌─ ]
│ ├─ #:
└────┤ ┌─ [:
└────┼─ i.
└─ / ─── *
5!:4 <'po2'
┌─ 3
── : ─┴─ ,:'|:y#:i.*/y'
,:'|:y#:i.*/y'
|:y#:i.*/y
$,:'|:y#:i.*/y'
1 10
;:',:''|:y#:i.*/y'''
┌──┬────────────┐
│,:│'|:y#:i.*/y'│
└──┴────────────┘
;:'|:y#:i.*/y'
┌──┬─┬──┬──┬─┬─┬─┐
│|:│y│#:│i.│*│/│y│
└──┴─┴──┴──┴─┴─┴─┘
Itemize and words! Now I can go to sleep!
Linda
-----Original Message-----
From: Programming <[email protected]> On Behalf Of Henry
Rich
Sent: Saturday, July 27, 2019 9:54 PM
To: [email protected]
Subject: Re: [Jprogramming] Learning Tacit Programming
The body of the explicit verb is considered to be a list of lines, i. e.
a rank-2 array of characters.
Henry Rich
On 7/27/2019 7:50 PM, Linda Alvord wrote:
> It seems not to matter that 1 is in parentheses:
>
> g=:13 :'1 x}y'
>
> 1 3 5 g i.10
> 0 1 2 1 4 1 6 7 8 9
>
> g
> 4 : '1 x}y'
>
> But hee is a surprise.
> Itemize (,:y) shows up.
>
> 5!:4 <'g'
> ┌─ 4
> ── : ─┴─ ,:'1 x}y'
>
> $'1 x}y'
> 5
>
> $,:'1 x}y'
> 1 5
> Why is this here?
>
> Linda
>
>
>
> -----Original Message-----
> From: Programming <[email protected]> On Behalf
> Of Roger Hui
> Sent: Saturday, July 27, 2019 1:06 AM
> To: [email protected]
> Subject: Re: [Jprogramming] Learning Tacit Programming
>
> 13 : '(1) x}y' or 13 : '1 x}y' can not be made tacit because they use a
> function argument (x) as an operand. Similarly 13 : '+/"y x' or 13 : '+/"x
> y' can not be made tacit either.
>
> Why not, you might ask? The sequence for an operator is that you _first_
> derive a function, and _then_ the function is applied to function arguments x
> and/or y . When you say x} or +/"x or +/"y , at that point you don't yet
> have the function argument.
>
>
>
> On Fri, Jul 26, 2019 at 9:40 PM Devon McCormick <[email protected]> wrote:
>
>> I am intrigued by tacit programming but agree with Henry that you
>> should drink the Kool-Aid with slow, measured sips.
>>
>> I continue to rely heavily on "13 : .." (to the dismay of tacit
>> die-hards) but still puzzle over why certain expressions cause it to give
>> up, e.g.
>>
>> 13 : '(1) x}y'
>> 4 : '(1) x}y'
>>
>> Yet this works
>> x=. 2 4 6
>> y=. i.10
>> (1) x}y
>> 0 1 1 3 1 5 1 7 8 9
>>
>> Whereas these do not:
>> x ((1) [}]) y
>> 0 1 2 3 4 5 6 7 8 9
>> x ((1)& [}]) y
>> 0 6 2 3 4 5 6 7 8 9
>>
>>
>> On Fri, Jul 26, 2019 at 11:53 PM Henry Rich <[email protected]> wrote:
>>
>>> Yes, you have to think differently.
>>>
>>> Please, don't make a fetish of tacit programming. The important
>>> thing about becoming a J programmer is training yourself to look at
>>> the whole problem rather than working with atoms. That is, getting
>>> over the loop mindset.
>>>
>>> Problem: You have an array a and you want to apply a linear function
>>> y=3x+1 to every atom. How do you do it?
>>>
>>> 0. (3 * a) + 1
>>> Bravo! You didn't have to loop. Full marks.
>>>
>>> 1. 1 + 3 * a
>>> Piu bravo! You are thinking right to left.
>>>
>>> 2. (1 + 3&*) a
>>> Bravissimo! You have written a little bit of tacit code. You could
>>> also have written (1 + 3 * ]) a
>>>
>>> 3. 1 3 p. a
>>> Congratulations, you have reached master level. Let the interpreter
>>> sweat the details.
>>>
>>>
>>> My very first J program was a model of texture processing for a
>>> computer-graphics system. I imbibed the tacit liquor too deeply,
>>> and wrote the whole thing as a sequence of tacit verbs, 50 of them.
>>> It worked. It was absolutely unmaintainable. Don't go there.
>>>
>>> Use tacit verbs for problems whose spec is mathematically unchangeable.
>>> For everything else, use explicit verbs.
>>>
>>> Henry Rich
>>>
>>>
>>>
>>>
>>>
>>> On 7/26/2019 7:20 PM, The3DSquare Josh Yang wrote:
>>>> I was wondering if you guys have any resources for learning tacit
>>>> programming in J. I've been struggling with tacit programming,
>>>> probably because all the other programming languages are mainly explicit.
>>> Something
>>>> like "Tacit programming for the explicit programmer" would be great
>>> since I
>>>> often fail to derive the tacit equivalent of a series of explicit
>>>> eeaxpressions (especially when there are mutable variables).
>>>>
>>>> I know I need to think differently, but having some guidance would
>>>> help greatly.
>>>> ------------------------------------------------------------------
>>>> ---- For information about J forums see http://w
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>>>> 6998007844844113&sdata=1N2L%2BXvxZpRcW5HmcfClWxo9xt%2Fi%2BYJXc
>>>> WkdRSmMDs8%3D&reserved=0
>>>
>>> ---
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>>
>> --
>>
>> Devon McCormick, CFA
>>
>> Quantitative Consultant
>> ---------------------------------------------------------------------
>> -
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