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Solving `Passport Application` with Haskell

(jameshaydon.github.io)
306 points jameshh | 1 comments | 28 Jun 25 23:01 UTC | HN request time: 0s | source
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behnamoh ◴[29 Jun 25 00:46 UTC] No.44409423[source]▶
Haskell has an interesting syntax: it is intuitive after someone explains it to me, but not intuitive much before the explanation.

I don't think it's because I'm used to Algol-based languages (C, Python, etc.). Every Haskell code I've seen is plagued with a plethora of operators which aim to make the code concise but it's not obvious what they do just by looking at them: https://academy.fpblock.com/haskell/tutorial/operators/

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tikhonj ◴[29 Jun 25 05:15 UTC] No.44410532[source]▶
At some point, I did a rough count, and the number of operators you encounter in "normal" Haskell code—avoiding lens or domain-specific libraries—was pretty close to the number of operators you'd encounter in, say, JavaScript. This was a while ago and I don't want to redo the exercise now, but, even if we're being generous to JavaScript, practical Haskell needs on the order of 2x as many operators as practical JavaScript, not 10x.

Haskell has some up-front incidental complexity, but it's a difference of degree not kind from popular starting languages. It's easy to underestimate how much you had to learn about Algol-style languages that you've just internalized so well that you don't even realize. I've taught some complete programming beginners (high or middle schoolers) Java and Python and, especially one-on-one, I've seen how they get confused by things I did not even remember required explanation!

For example, in Python, people put : in the wrong place and don't understand how = works. "Basic" syntax like : and = are far more complex than we realize, we've just learned the basics so well that it's second nature. It's similar to how native English speakers don't even realize we have rules for adjective order ("big red ball" vs "red big ball"), while language learners run into it like a brick wall.

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1. ngruhn ◴[29 Jun 25 07:09 UTC] No.44410908[source]▶
I don't know if you just counted the JavaScript operators but if you count all the instances where some random symbol is used then it's really a ton. There is

    yield*
    function*
    a?.b?.c
    function f(x = 3) {
    x ??= 3
    ...
TypeScript adds even more:

    a!.b
    Type<T>
    type A = B extends C ? D : E
    ...
and there are countless ECMA proposals and TypeScript feature request that want to pile on even more. People seem to have zero qualms about cryptic syntax. I think the difference is that this syntax is mostly very ad-hoc. If you know the language already, this just adds a liiiittle bit extra to solve some very specific problem. On the other hand, Haskell operators like <$>, <*>, >>= are extremely general. After years I still learn about new and unexpected ways that you can use them (e.g. what the hell is `fix <$> id`). But paradoxically, because they can be used in so many seemingly unrelated contexts, you have no idea what to use them for at all initially.