4 ms·

Mostly irrelevant but those runtime errors are the main reason why I stopped using Haskell. Haskell is a great language with a great booming ecosystem, but if y

by tinco 4y ago

Mostly irrelevant but those runtime errors are the main reason why I stopped using Haskell. Haskell is a great language with a great booming ecosystem, but if you can have uncaught exceptions in IO monads, and even unchecked errors in your pure code like that fromJust there, then what's the point? For all its ceremony is not much more functionally pure than JavaScript. And a language without purity as a concept like Rust has achieved frankly a more tight feeling of safety and great flexibility despite having a more simple typesystem. Imo Haskell has to drastically change like it did in the early 2000's to become competitive again.

dan-dev 4y ago
Hold on! See: https://github.com/dan-blank/hgrep-smallcore/issues/1 https://github.com/dan-blank/hgrep-smallcore/issues/1 Using `fromJust` is deeply frowned upon, and indeed a few eyebrows were raised then showing my code to the examiners. This and a handful other warts unfortunate, but few and easy to work around. This function and others are in the prelude, but one can use other preludes that don't have these escape hatches. This does not undermine the huge benefits that people get from having IO checked by the typesystem. Just as having tyepcasting in a language does not undermine the benefits of types in that language.
- tinco 4y ago
  IO isn't checked by the type system if errors aren't checked by the type system. Haskell could be better, Haskell should have been better.
  - dan-dev 4y ago
    Nah, the type system is perfectly fine in this case: "Given (Just someValue), return someValue". Exactly what happened here, the precondition just was not fulfilled and I left the case dealing the unfulfilled precondition undefined. If one cares about such things, one should simply use one of the numerous alternative Preludes out there (to make sure to actually never use fromMaybe, head and the 3 other functions that nobodoy uses form the standard Prelude) and turn the warnings for incomplete pattern matches on. At least, thats how you could deal with it in real life. If it is not practical matters that are the concern here, there are more than enough languages that only allow total functions and offer other sweet stuff. Haskell's main purpose was to be a lazy-by-default-language, and that people can actually write practical stuff in it is a nice side-effect.
burntsushi 4y ago
I'm unconvinced by such things. From what I can tell, this is academia code. In academia code, regardless of programming language, folks often don't care about failure modes. (I speak from experience, as someone who used to be in academia.) So I'd be more inclined to pin it on academia's incentive structure than anything about programming languages. I suppose you could use a programming environment that forbids partial functions, but I'm unclear on how productive that is. > And a language without purity as a concept like Rust has achieved frankly a more tight feeling of safety and great flexibility despite having a more simple typesystem. Haskell has 'fromJust' and Rust has 'unwrap'. They're both exactly equivalent and result in similarly poor failure modes. (Well, 'unwrap' usually at least gives you a line number.)
- tinco 4y ago
  Yeah, but even better Rust has `except`, but that's besides the point. Rust doesn't pretend to by a pure language, it just promises to be a safe language as long as you don't use `unsafe`. Haskell makes a big fuss about how it's pure and productive because you have fewer bugs. And this is true as long as you're writing pure data processing or algorithmic code. But as soon as you stray from that and try to build a practical program, you'll need the IO monad and it sucks, even Java deals better with exceptions than Haskell. All the type class expressiveness in the world, and they couldn't figure out how to model exceptions. And it used to be that Haskell could just introduce backwards incompatible changes because it was a research language. But now Haskell is used widely in production, and even though it's in desperate need of a new Prelude, it's not gonna happen. When someone who truly believed in that Haskell could be a proper modern programming tool and invested their hard work and frankly their genius into it, they Haskell leadership responded with skepticism and inaction. I bet if you gave Snoyman full dictatorship over a new Haskell prelude, it would be the best general purpose programming language by a mile for the next decade at least. Instead Haskell will remain as backwards as its ISO 8859-1 String type.
  - burntsushi 4y ago
    Yeah I think you're going places I don't care to follow. We were talking about a specific program, and I made the argument that the behavior of the program was more sharply determined by the incentive structure in which it was written. But you're kind of doubling down into a more general rant about Haskell that is actually totally divorced from the failure mode of the Haskell program in question. I used to use Haskell too and I stopped using it for $reasons. Nothing to do with the prelude or its string type though. More about the nature of the language and paradigm itself.

by tinco 4y ago

dan-dev 4y ago

Hold on! See: https://github.com/dan-blank/hgrep-smallcore/issues/1 https://github.com/dan-blank/hgrep-smallcore/issues/1 Using `fromJust` is deeply frowned upon, and indeed a few eyebrows were raised then showing my code to the examiners. This and a handful other warts unfortunate, but few and easy to work around. This function and others are in the prelude, but one can use other preludes that don't have these escape hatches. This does not undermine the huge benefits that people get from having IO checked by the typesystem. Just as having tyepcasting in a language does not undermine the benefits of types in that language.

tinco 4y ago
IO isn't checked by the type system if errors aren't checked by the type system. Haskell could be better, Haskell should have been better.
- dan-dev 4y ago
  Nah, the type system is perfectly fine in this case: "Given (Just someValue), return someValue". Exactly what happened here, the precondition just was not fulfilled and I left the case dealing the unfulfilled precondition undefined. If one cares about such things, one should simply use one of the numerous alternative Preludes out there (to make sure to actually never use fromMaybe, head and the 3 other functions that nobodoy uses form the standard Prelude) and turn the warnings for incomplete pattern matches on. At least, thats how you could deal with it in real life. If it is not practical matters that are the concern here, there are more than enough languages that only allow total functions and offer other sweet stuff. Haskell's main purpose was to be a lazy-by-default-language, and that people can actually write practical stuff in it is a nice side-effect.

burntsushi 4y ago

I'm unconvinced by such things. From what I can tell, this is academia code. In academia code, regardless of programming language, folks often don't care about failure modes. (I speak from experience, as someone who used to be in academia.) So I'd be more inclined to pin it on academia's incentive structure than anything about programming languages. I suppose you could use a programming environment that forbids partial functions, but I'm unclear on how productive that is. > And a language without purity as a concept like Rust has achieved frankly a more tight feeling of safety and great flexibility despite having a more simple typesystem. Haskell has 'fromJust' and Rust has 'unwrap'. They're both exactly equivalent and result in similarly poor failure modes. (Well, 'unwrap' usually at least gives you a line number.)

tinco 4y ago
Yeah, but even better Rust has `except`, but that's besides the point. Rust doesn't pretend to by a pure language, it just promises to be a safe language as long as you don't use `unsafe`. Haskell makes a big fuss about how it's pure and productive because you have fewer bugs. And this is true as long as you're writing pure data processing or algorithmic code. But as soon as you stray from that and try to build a practical program, you'll need the IO monad and it sucks, even Java deals better with exceptions than Haskell. All the type class expressiveness in the world, and they couldn't figure out how to model exceptions. And it used to be that Haskell could just introduce backwards incompatible changes because it was a research language. But now Haskell is used widely in production, and even though it's in desperate need of a new Prelude, it's not gonna happen. When someone who truly believed in that Haskell could be a proper modern programming tool and invested their hard work and frankly their genius into it, they Haskell leadership responded with skepticism and inaction. I bet if you gave Snoyman full dictatorship over a new Haskell prelude, it would be the best general purpose programming language by a mile for the next decade at least. Instead Haskell will remain as backwards as its ISO 8859-1 String type.
- burntsushi 4y ago
  Yeah I think you're going places I don't care to follow. We were talking about a specific program, and I made the argument that the behavior of the program was more sharply determined by the incentive structure in which it was written. But you're kind of doubling down into a more general rant about Haskell that is actually totally divorced from the failure mode of the Haskell program in question. I used to use Haskell too and I stopped using it for $reasons. Nothing to do with the prelude or its string type though. More about the nature of the language and paradigm itself.