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Re: [Bug-apl] The Dyalog ⌸ operator

From: Elias Mårtenson
Subject: Re: [Bug-apl] The Dyalog ⌸ operator
Date: Wed, 27 Apr 2016 13:00:45 +0800

The Dyalog language reference guide contains all the Dyalog stuff: http://docs.dyalog.com/14.1/Dyalog%20APL%20Language%20Reference.pdf

In particular, ⍤ is described on page 146, and ⌸ on page 139.

The formal ISO APL specification can be downloaded here: http://www.math.uwaterloo.ca/~ljdickey/apl-rep/docs/is13751.pdf

Note that for the last link, the file is actually gzipped, so you have to uncompress it before you can read it.


On 27 April 2016 at 12:41, Christian Robert <address@hidden> wrote:
where are you taking the definition of various functions like ?

power operator ?

dieresis jot ? like: (⊂⍤1) z,⍪z  (I really don't know what it is doing)

I see no references anywhere on the web. None in apl2 manual, none in Dyalog manual.

how can I learn thoses ...  without a manual and/or some examples ?


On 2016-04-26 23:02, Elias Mårtenson wrote:
I was reading about the Dyalog "key" operator ⌸. It's certainly a useful function, and something that should probably be added to GNU APL, in my opinion.

As always when thinking about useful additions to GNU APL, I wanted to try to do some things that ⌸ can do, without having access to it.

So, I wanted to simply take a string of characters, and create a list of each character and the number of occurrences of each character in that string. My solution works, but feels clumsy:

*       { ⊃{(↑⍵) (↑⍴⍵)}¨(⎕UCS v) ⊂ v←⍵[⍋⍵] } "abcfoobat"*
↓'a' 2┃
┃'b' 2┃
┃'c' 1┃
┃'f' 1┃
┃'o' 2┃
┃'t' 1┃

Can anyone improve this? In particular, can it be improved to the point of convincing me that ⌸ is not needed?


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