> Array programming is similar to functional programming – the primary way to control execution involves composition of functions – but APL tends to encourage the reliance on global properties and sweeping operations rather than low-level recursion4.
This AoC solution is, indeed, quite the functionista! Better yet, it leans heavily into point-free expressions. The style is pretty popular amongst APL language enthusiasts and puzzlers.
That said, you actually see quite different APL styles in the wild:
- Pointed declarative style, also a popular with functional programmers (e.g. anything like this[0] from the dfns workspace)
- Imperative, structured programming, very common in legacy production systems (e.g. this[1] OpenAI API interface)
- Object-oriented, also common in somewhat newer production environments (e.g. the HTTP interface[2])
- Data-parallel style (e.g. Co-dfns[3])
Heck, APL even has lexical and dynamic scope coexisting together. IMHO, it's truly underrated as a language innovator.
My favorite language used to interpret my most hated language (used both professionally).
There are several things I disagree with regarding Haskell but it's understandable given that this is OP's first time using the language (like a "monad's internal state"), but I want to highlight one particular observation:
> This uncertainty of time of evaluation also makes catching errors difficult, because calling catch on the function that throws the error will not necessarily catch that error
It's important to distinguish between imprecise exceptions (ex. calls to `error `, `undefined`, and the like) and synchronous exceptions (async exceptions are not important for the article).
> Catch must be called on the function that forces evaluation on that error. This is something that is hard to trace, and something that types don’t help much with.
The types are actually the most important part here! Synchronous exceptions cannot be thrown by pure code (as long as we're not dealing with escape hatches like `unsafePerformIO`), while IO code can throw and catch all kind of exceptions .
0xTJ · 6h ago
Seeing "all built-in functions and operators are single unicode symbols" stood out to me, given that APL existed well before Unicode did. It's not that it's wrong today, but that wasn't always the case. My father used APL back in high school, and that was before the earliest year mentioned in the "History" section of the Unicode Wikipedia article.
howerj · 7h ago
Is there an implementation of an APL language (or other any other array language) written in *readable* C that is around 1000 LoC? There are for LISP, FORTH, Prolog, TCL and the like.
Note, these aren't APL, but they are in the same family of array languages.
xelxebar · 4h ago
Unlikely, at least for what I think you mean by "readable" here.
APL isn't really one of these exhibitions of computational simplicity in the way of the languages you mention. It's inventor, Kenneth Iverson, was more focused on the human side of thinking in and using the language.
Forth, Lisp, et al are quite easy to implement, but they require considerable library layers on top to make them useful for expressing application-level logic, even if we just focus on the pure functions. APL, on the other hand, has a larger core set of primitives, but you're then immediately able to concisely express high-level application logic.
Are you looking for a kind of reference implementation for learning purposes? If so, I'd say the best route is just go with the docs. Arguably the Co-dfns compiler is a precise spec, but it's notably alien to non-practitioners.
ofalkaed · 4h ago
Any pointers on how to get better at expressing high-level application logic in APL? Any good resources on programming in APL? So far I have only found tutorials and basic stuff for learning APL but not much on applying APL. I am slowly improving and think I sort of get it but probably don't.
xelxebar · 3h ago
Not that I know of, unfortunately. This is, IMHO, the biggest pain point of APL pedagogy at the moment. I'm actually working on some resources, but they're still gestating.
For non-event driven systems, the short story is to organize application state as a global database of inverted tables and progressively normalize them such that short APL expressions carry the domain semantics you want.
For event driven systems, we have token enumeration over state machines, which can be expressed as literal Branches to state blocks.
Granted, the above likely doesn't communicate well unless you're already primed with all the necessary ideas. If you're interested, I'm willing to chat. Email is in my profile description.
source: Current day-to-day is greenfield APL dev.
ofalkaed · 7h ago
Not that I have found, closest is an incomplete one done in python.
Depending on your personality type (perfectionist or pragmatic), this is either the best of both worlds or the worst.
instig007 · 8h ago
> Apparently Haskell’s performance isn’t that bad, but I don’t plan on using Haskell for anything that is remotely performance-sensitive. Trying to optimize Haskell code does sound like an interesting problem, but it might be a lost cause.
When the dude uses `foldl` over lists and `foldr` with `(*)` (numeric product) it is not the language that's the lost cause.
kccqzy · 7h ago
In case anyone who doesn't know Haskell: both of these are beginner level mistakes. Using `foldl` causes space leaks and turns your O(1) space algorithm to O(N) space for no good reason. And using `foldr` over lists is good when you are dealing with unevaluated lists and want list fusion, but not when they already exist in memory and will continue to do so. And that doesn't even include the obviously wrong choice of data structure, built-in Haskell lists are singly-linked lists not arrays. There are Array types and Vector types (both come with GHC so no extra dependency needed) that are more appropriate for implementing APL in the first place.
itishappy · 6h ago
> And using `foldr` over lists is good when you are dealing with unevaluated lists and want list fusion, but not when they already exist in memory and will continue to do so.
What's the preffered approach?
farrellm23 · 6h ago
Usually you want `foldl'` (with ' at the end), the strict version of `foldl`. It prevents the creation of intermediate thunks, so effectively a tail recursive iteration over the list in constant space.
`foldr` I almost never use, but it would be for: the return value is a lazy list and I will only need to evaluate a prefix.
nickzelei · 7h ago
Interesting read!
On a semi-related topic: I tried learning Haskell this past weekend out of curiosity that I last tried it some 10+ years ago while still in college.
I found resources for it scant. Coming from more modern languages/tooling like Go/Rust, I also struggled quite a bit with installation and the build/package system.
I tried the stack template generator for yesod/sqlite and after some 15 minutes of it installing yet another GHC version and building, I eventually ctrl+C'd and closed out of the window.
Maybe this was a unique experience, but I'd love some guidance on how to be successful with Haskell. I've primarily spent most of my professional years building web services, so that was the first place I went to. However, I was taken aback by how seemingly awful the setup and devex was for me. I've always been interested in functional programming, and was looking to sink my teeth in to a language where there is no other option.
itishappy · 7h ago
My understanding is that Cabal has more or less supplanted Stack. Use GHCup to install everything, then use `cabal init`, `cabal run`, or `cabal repl` like you would in Go/Rust.
Stack builds on top of Cabal, and used to solve a bunch of problems, but the reasons for it's existence are no longer super relevant. It still works totally fine if that's your thing though.
As for being successful, there are several nice books, and several active forums. I've gotten good answers on the Libera IRC network #haskell channel, and on the Haskell matrix channel #haskell:matrix.org
I learned using the Haskell Programming from First Principles book (haskellbook.com). I don't think it goes into web development, but it certainly goes through the basic project setup.
Do you think you would have benefitted from a resource like the Rust book? I've been toying with the idea of writing something similar and donating it to the Haskell Foundation
This AoC solution is, indeed, quite the functionista! Better yet, it leans heavily into point-free expressions. The style is pretty popular amongst APL language enthusiasts and puzzlers.
That said, you actually see quite different APL styles in the wild:
- Pointed declarative style, also a popular with functional programmers (e.g. anything like this[0] from the dfns workspace)
- Imperative, structured programming, very common in legacy production systems (e.g. this[1] OpenAI API interface)
- Object-oriented, also common in somewhat newer production environments (e.g. the HTTP interface[2])
- Data-parallel style (e.g. Co-dfns[3])
Heck, APL even has lexical and dynamic scope coexisting together. IMHO, it's truly underrated as a language innovator.
[0]:https://dfns.dyalog.com/c_match.htm
[1]:https://github.com/Dyalog/OpenAI/blob/main/source/OpenAI.apl...
[2]:https://github.com/Dyalog/HttpCommand/blob/master/source/Htt...
[3]:https://github.com/Co-dfns/Co-dfns/blob/master/cmp/PS.apl
There are several things I disagree with regarding Haskell but it's understandable given that this is OP's first time using the language (like a "monad's internal state"), but I want to highlight one particular observation:
> This uncertainty of time of evaluation also makes catching errors difficult, because calling catch on the function that throws the error will not necessarily catch that error
It's important to distinguish between imprecise exceptions (ex. calls to `error `, `undefined`, and the like) and synchronous exceptions (async exceptions are not important for the article).
> Catch must be called on the function that forces evaluation on that error. This is something that is hard to trace, and something that types don’t help much with.
The types are actually the most important part here! Synchronous exceptions cannot be thrown by pure code (as long as we're not dealing with escape hatches like `unsafePerformIO`), while IO code can throw and catch all kind of exceptions .
https://www.jsoftware.com/ioj/iojATW.htm
https://github.com/kparc/ksimple/blob/main/ref/a.c
Slightly less factiously, the ksimple repository has a version with comments.
https://github.com/kparc/ksimple
https://github.com/kparc/ksimple/blob/main/a.c
Note, these aren't APL, but they are in the same family of array languages.
APL isn't really one of these exhibitions of computational simplicity in the way of the languages you mention. It's inventor, Kenneth Iverson, was more focused on the human side of thinking in and using the language.
Forth, Lisp, et al are quite easy to implement, but they require considerable library layers on top to make them useful for expressing application-level logic, even if we just focus on the pure functions. APL, on the other hand, has a larger core set of primitives, but you're then immediately able to concisely express high-level application logic.
Are you looking for a kind of reference implementation for learning purposes? If so, I'd say the best route is just go with the docs. Arguably the Co-dfns compiler is a precise spec, but it's notably alien to non-practitioners.
For non-event driven systems, the short story is to organize application state as a global database of inverted tables and progressively normalize them such that short APL expressions carry the domain semantics you want.
For event driven systems, we have token enumeration over state machines, which can be expressed as literal Branches to state blocks.
Granted, the above likely doesn't communicate well unless you're already primed with all the necessary ideas. If you're interested, I'm willing to chat. Email is in my profile description.
source: Current day-to-day is greenfield APL dev.
https://mathspp.com/blog/tag:lsbasi-apl#body-wrapper
When the dude uses `foldl` over lists and `foldr` with `(*)` (numeric product) it is not the language that's the lost cause.
What's the preffered approach?
`foldr` I almost never use, but it would be for: the return value is a lazy list and I will only need to evaluate a prefix.
On a semi-related topic: I tried learning Haskell this past weekend out of curiosity that I last tried it some 10+ years ago while still in college.
I found resources for it scant. Coming from more modern languages/tooling like Go/Rust, I also struggled quite a bit with installation and the build/package system.
I tried the stack template generator for yesod/sqlite and after some 15 minutes of it installing yet another GHC version and building, I eventually ctrl+C'd and closed out of the window.
Maybe this was a unique experience, but I'd love some guidance on how to be successful with Haskell. I've primarily spent most of my professional years building web services, so that was the first place I went to. However, I was taken aback by how seemingly awful the setup and devex was for me. I've always been interested in functional programming, and was looking to sink my teeth in to a language where there is no other option.
Stack builds on top of Cabal, and used to solve a bunch of problems, but the reasons for it's existence are no longer super relevant. It still works totally fine if that's your thing though.
As for being successful, there are several nice books, and several active forums. I've gotten good answers on the Libera IRC network #haskell channel, and on the Haskell matrix channel #haskell:matrix.org
If you want to get started without installing anything, there's the exercism track: https://exercism.org/tracks/haskell
I've heard good things about Brent Yorgey's Haskell course ( https://www.cis.upenn.edu/~cis1940/spring13/lectures.html ) but haven't tried it myself.
Do you think you would have benefitted from a resource like the Rust book? I've been toying with the idea of writing something similar and donating it to the Haskell Foundation