5 ms·

APL in JavaScript

77 points by smanuel 13y ago

beagle3 13y ago
Live Coding example showing Life in APL: http://www.youtube.com/watch?v=a9xAKttWgP4 http://www.youtube.com/watch?v=a9xAKttWgP4 I generally hate videos, but this one is well worth the few minutes it takes (assuming you are not familiar with APL; read the examples on the linked page first, it will save you a couple of reviews of the videos until you get it all)
mikeryan 13y ago
For those (like me) who didn't know, APL is a programming language... http://en.wikipedia.org/wiki/APL_(programming_language) http://en.wikipedia.org/wiki/APL_(programming_language)
- ctdonath 13y ago
  Correction: APL is A Programming Language. And one so dense/obscure/efficient that obfuscation is not a contest, it's an inherent philosophy. Edit: corrected misuse of "obtuse".
  - gruseom 13y ago
    APL isn't obtuse—just unfamiliar to people who aren't familiar with it. By the dictionary meaning of 'obtuse', in fact, APL is the opposite: a sharp tool and a masterpiece of design.
    - Locke1689 13y ago
      I wouldn't describe it as obtuse, but I would describe it as concise. I think that even people who are familiar with it could feel that its concision hurts readability. It's not such an unfair criticism as you may suggest.
      - LfLxfxxLxfxx 13y ago
        I've observed two reasons people perceive APL code as unreadable: 1. They are not familiar with the symbols. It's the equivalent of trying to read a label in a foreign language. The text may seem unreadable to you, but if you learn the alphabet/hieroglyphs and some vocab, it makes sense. 2. They aren't used to brevity of notation. An APL program is to be read character by character, the way one reads a Java program line by line. Brevity is an advantage because it allows you to see more of a program's structure at a glance.
      - doublec 13y ago
        Ken Iverson wrote an interesting document, "Notation as a tool of thought", which covers his thoughts on what a concise/efficient notation provides: http://www.jsoftware.com/papers/tot.htm http://www.jsoftware.com/papers/tot.htm
        Locke1689 13y ago
        Really, interesting, thank you! The one worry I have with APL and its descendants is that its conciseness will encourage people to make overly long expressions. One possibly beneficial side-effect of more verbose languages is that it tends to encourage the use of additional identifiers to hold sub-expressions. The act of naming things is often a good thing for both the authors and readers of a program. More abstractly, it allows the program to carry intentional semantics alongside operational semantics. This is also a problem I have with mathematics -- mathematical notation often uses context-dependent single-letter variable names for semantic information, which is terrible from an outsider's perspective (and by outsider I really mean anyone who isn't working in the exact field of the mathematician). Edit: I should mention that I'm still pretty enamored with J for numerical computation, even though I never do any of it :)
        gruseom 13y ago
        If you like the Iverson, don't miss the famous piece of Whitehead's where he talks about notation too: http://introtologic.info/AboutLogicsite/whitehead%20Good%20Notation.html http://introtologic.info/AboutLogicsite/whitehead%20Good%20N... Iverson took one of his epigraphs from there, but the whole thing is short and well worth reading. Fun fact: Iverson, Roger Hui (the J guy) and Arthur Whitney (the K guy) were all from Alberta.
    - sysop073 13y ago
      "just unfamiliar to people who aren't familiar with it". That was deep
      - gruseom 13y ago
        That was intentional. Calling a language unreadable is a kind of tautology, because it contains no information about the language, only the reader. Is Sanksrit readable? Saying "that's not readable" about APL is about as foolish as saying it about Sanskrit.
DonGateley 13y ago
Quibble. The demo should allow use of the computer's keyboard and Alt key. Point and click with a graphical keyboard is nuts. It should support overstrike for APL's composite symbols. I did a whole lot of APL programming in the '60s and '70s at IBM and consider it IBM's bastard child. There need not have been Matlab. I'm appalled by the authors enforcement of 1-origin indexing.
- LfLxfxxLxfxx 13y ago
  Try typing backquote followed by another character. I believe mapping alt+key in the browser might be difficult. It's 0-origin indexing.
  - DonGateley 13y ago
    "Try typing backquote followed by another character." Sorry, I don't follow? "It's 0-origin indexing." Oops. Then I'm ecstatic rather than appalled. :-)
    - LfLxfxxLxfxx 13y ago
      "Try typing backquote followed by another character." I mean the text box at http://ngn.github.io/apl/web/index.html http://ngn.github.io/apl/web/index.html If you type for instance `r in it, you will get a rho symbol, `i for iota, `a `w for alpha and omega, etc
DonGateley 13y ago
I find the GitHub project but can find nothing explaining how to install and use it. Can anyone point me in the right direction?

77 points by smanuel 13y ago

Live Coding example showing Life in APL: http://www.youtube.com/watch?v=a9xAKttWgP4 http://www.youtube.com/watch?v=a9xAKttWgP4 I generally hate videos, but this one is well worth the few minutes it takes (assuming you are not familiar with APL; read the examples on the linked page first, it will save you a couple of reviews of the videos until you get it all)

mikeryan 13y ago

For those (like me) who didn't know, APL is a programming language... http://en.wikipedia.org/wiki/APL_(programming_language) http://en.wikipedia.org/wiki/APL_(programming_language)

ctdonath 13y ago
Correction: APL is A Programming Language. And one so dense/obscure/efficient that obfuscation is not a contest, it's an inherent philosophy. Edit: corrected misuse of "obtuse".
- gruseom 13y ago
  APL isn't obtuse—just unfamiliar to people who aren't familiar with it. By the dictionary meaning of 'obtuse', in fact, APL is the opposite: a sharp tool and a masterpiece of design.
  - Locke1689 13y ago
    I wouldn't describe it as obtuse, but I would describe it as concise. I think that even people who are familiar with it could feel that its concision hurts readability. It's not such an unfair criticism as you may suggest.
    - LfLxfxxLxfxx 13y ago
      I've observed two reasons people perceive APL code as unreadable: 1. They are not familiar with the symbols. It's the equivalent of trying to read a label in a foreign language. The text may seem unreadable to you, but if you learn the alphabet/hieroglyphs and some vocab, it makes sense. 2. They aren't used to brevity of notation. An APL program is to be read character by character, the way one reads a Java program line by line. Brevity is an advantage because it allows you to see more of a program's structure at a glance.
    - doublec 13y ago
      Ken Iverson wrote an interesting document, "Notation as a tool of thought", which covers his thoughts on what a concise/efficient notation provides: http://www.jsoftware.com/papers/tot.htm http://www.jsoftware.com/papers/tot.htm
      - Locke1689 13y ago
        Really, interesting, thank you! The one worry I have with APL and its descendants is that its conciseness will encourage people to make overly long expressions. One possibly beneficial side-effect of more verbose languages is that it tends to encourage the use of additional identifiers to hold sub-expressions. The act of naming things is often a good thing for both the authors and readers of a program. More abstractly, it allows the program to carry intentional semantics alongside operational semantics. This is also a problem I have with mathematics -- mathematical notation often uses context-dependent single-letter variable names for semantic information, which is terrible from an outsider's perspective (and by outsider I really mean anyone who isn't working in the exact field of the mathematician). Edit: I should mention that I'm still pretty enamored with J for numerical computation, even though I never do any of it :)
        gruseom 13y ago
        If you like the Iverson, don't miss the famous piece of Whitehead's where he talks about notation too: http://introtologic.info/AboutLogicsite/whitehead%20Good%20Notation.html http://introtologic.info/AboutLogicsite/whitehead%20Good%20N... Iverson took one of his epigraphs from there, but the whole thing is short and well worth reading. Fun fact: Iverson, Roger Hui (the J guy) and Arthur Whitney (the K guy) were all from Alberta.
  - sysop073 13y ago
    "just unfamiliar to people who aren't familiar with it". That was deep
    - gruseom 13y ago
      That was intentional. Calling a language unreadable is a kind of tautology, because it contains no information about the language, only the reader. Is Sanksrit readable? Saying "that's not readable" about APL is about as foolish as saying it about Sanskrit.

DonGateley 13y ago

Quibble. The demo should allow use of the computer's keyboard and Alt key. Point and click with a graphical keyboard is nuts. It should support overstrike for APL's composite symbols. I did a whole lot of APL programming in the '60s and '70s at IBM and consider it IBM's bastard child. There need not have been Matlab. I'm appalled by the authors enforcement of 1-origin indexing.

LfLxfxxLxfxx 13y ago
Try typing backquote followed by another character. I believe mapping alt+key in the browser might be difficult. It's 0-origin indexing.
- DonGateley 13y ago
  "Try typing backquote followed by another character." Sorry, I don't follow? "It's 0-origin indexing." Oops. Then I'm ecstatic rather than appalled. :-)
  - LfLxfxxLxfxx 13y ago
    "Try typing backquote followed by another character." I mean the text box at http://ngn.github.io/apl/web/index.html http://ngn.github.io/apl/web/index.html If you type for instance `r in it, you will get a rho symbol, `i for iota, `a `w for alpha and omega, etc

DonGateley 13y ago

I find the GitHub project but can find nothing explaining how to install and use it. Can anyone point me in the right direction?