5 ms·

Introduction to APL

31 points by fogus 16y ago

silentbicycle 16y ago
J (http://www.jsoftware.com/ http://www.jsoftware.com/) is a modern and free (though not open source) APL dialect. It has some of the best documentation I've seen for any language, ever. Q (http://kx.com/ http://kx.com/ , previously known as K) is also pretty amazing, but unfortunately isn't free.
nimrody 16y ago
Does a language like APL/J really offer something more than other matrix/math oriented languages (Matlab comes to mind)? Other than extreme conciseness (unreadable at times).
- silentbicycle 16y ago
  Making looping implicit seems to have huge benefits, in particular. It shrinks the code down quite a bit, much like the implicit search does in Prolog. As for the unreadability - I can't read Turkish, but that has more to do with me than Turkish. Good APL really isn't that hard to read: The syntax is incredibly consistent, and while unfamiliar symbols are used, there aren't that many, and most are mnemonic - for example, the reverse operator is a circle with a vertical line through it, like a semicircle being mirrored.
- rbanffy 16y ago
  > Other than extreme conciseness (unreadable at times). I have to agree with that. My APL programs were the epitome of write-only code. Even with comments, the magic being performed on the one-liner after them could hardly be described in less than 10 lines. I suspect good APL programs have a comment to code ratio of more than 10.
- beagle3 16y ago
  Extreme conciseness, though sometimes unreadable, is often helpful in the sense that you can fit 3000 line Java programs on one 50 line screen -- no scrolling to look things up. It doesn't mean it takes 1/60 time to read through it -- I would guess 1/5 is more like it (assuming you are competent in the language you are reading, which is a steeper learning curve for J/K/Q/APL). Personally, having everything on the screen at the same time is very useful. Also, as J and especially K prove, extreme runtime speed is also attainable. You can beat it with C code -- after all, the K interpreter is written in C. But more often, K pushes you towards a concise implementation that the interpreter blazes through, whereas in C you'd probably not go to the effort all the time and result in slower code at the end.

31 points by fogus 16y ago

J (http://www.jsoftware.com/ http://www.jsoftware.com/) is a modern and free (though not open source) APL dialect. It has some of the best documentation I've seen for any language, ever. Q (http://kx.com/ http://kx.com/ , previously known as K) is also pretty amazing, but unfortunately isn't free.

nimrody 16y ago

Does a language like APL/J really offer something more than other matrix/math oriented languages (Matlab comes to mind)? Other than extreme conciseness (unreadable at times).

silentbicycle 16y ago
Making looping implicit seems to have huge benefits, in particular. It shrinks the code down quite a bit, much like the implicit search does in Prolog. As for the unreadability - I can't read Turkish, but that has more to do with me than Turkish. Good APL really isn't that hard to read: The syntax is incredibly consistent, and while unfamiliar symbols are used, there aren't that many, and most are mnemonic - for example, the reverse operator is a circle with a vertical line through it, like a semicircle being mirrored.
rbanffy 16y ago
> Other than extreme conciseness (unreadable at times). I have to agree with that. My APL programs were the epitome of write-only code. Even with comments, the magic being performed on the one-liner after them could hardly be described in less than 10 lines. I suspect good APL programs have a comment to code ratio of more than 10.
beagle3 16y ago
Extreme conciseness, though sometimes unreadable, is often helpful in the sense that you can fit 3000 line Java programs on one 50 line screen -- no scrolling to look things up. It doesn't mean it takes 1/60 time to read through it -- I would guess 1/5 is more like it (assuming you are competent in the language you are reading, which is a steeper learning curve for J/K/Q/APL). Personally, having everything on the screen at the same time is very useful. Also, as J and especially K prove, extreme runtime speed is also attainable. You can beat it with C code -- after all, the K interpreter is written in C. But more often, K pushes you towards a concise implementation that the interpreter blazes through, whereas in C you'd probably not go to the effort all the time and result in slower code at the end.