Hacker News Reader

Comment by randomdata | Hacker News Reader

> Except for all those times you're the consumer of someone else's library and there's no way for them to indicate that creating a zero-valued struct is a bug.

Nonsense. Go has a built-in facility for documentation to communicate these things to other developers. Idiomatic Go strongly encourages you to use it. Consumers of the libraries expect it.

> Sometimes it's nice to work with a type system where designers of libraries can actually prevent you from writing bugs.

Well, sure. But, like I said, almost nobody uses Coq. The vast, vast, vast majority of projects – and I expect 100% of web projects – use languages with incomplete type systems, making what you seek impossible.

And there's probably a good reason for that. While complete type systems sound nice in theory, practice isn't so kind. There are tradeoffs abound. There is no free lunch in life. Sorry.

View on HN

> The vast, vast, vast majority of projects – and I expect 100% of web projects – use languages with incomplete type systems, making what you seek impossible.

…where, "what GP seeks" is…

> way for [library authors] to indicate that creating a zero-valued struct is a bug

I'd say that's a really low and practical bar, you really don't need Coq for that. Good old Python is enough, even without linters and type hints.

Of course it's very easy to create an equivalent of zero struct (object without __init__ called), but do you think it's possible to do it while not noticing that you are doing something unusual?

> Good old Python is enough

No, Python is not enough to "...work with a type system where designers of libraries can actually prevent you from writing bugs." Not even typed Python is going to enable that. Only a complete type system can see the types prevent you from writing those bugs. And I expect exactly nobody is writing HTTP services with a language that has a complete type system – for good reason.

> Of course it's very easy to create an equivalent of zero struct

Yes, you are quite right that you, the library consumer, can Foo.__new__(Foo) and get an object that hasn't had its members initialized just like you can in Go. But unless the library author has specifically called attention to you to initialize the value this way, that little tingling sensation should be telling you that you're doing something wrong. It is not conventional for libraries to have those semantics. Not in Python, not in Go.

Just because you can doesn't mean you should.

You don't have to go as far as Coq. Rust manages "parse, don't validate" extremely well with serde.

Go's zero-values are the problem, not any other lack of its type system.

> You don't have to go as far as Coq.

No, you do. Anywhere the type system is incomplete means that the consumer can do something the library didn't intend. Rust does not have a complete type system. There was no relevance to mentioning it. But I know it is time for Rust's regularly scheduled ad break. And while you are at it, enjoy a cool, refreshing Coca-Cola.

> Go's zero-values are the problem

"Sometimes it's nice to work with a type system where designers of libraries can actually prevent you from writing bugs." has nothing to do with zero-values. It doesn't even really have anything to do with Go specifically. My, the quality of advertising has really declined around here. Used to be the Rust ads at least tried to look like they fit in.

This insane perspective of “nothing is totally perfect so any improvements over what go currently does are pointless” whenever you confront a gopher with some annoying quirk of the language is one of the worst design flaws in the golang community hivemind.

Tell us, why you hold that perspective? It's an odd one. Nobody else in this thread holds that perspective. You even admit it is insane, yet here you are telling us about this unique perspective you hold for some reason. Are you hoping that we will declare you insane and admit you in for care? I don't quite grasp the context you are trying to work within.

Any language without zero-values (or some equally destructive quality) can do "parse, don't validate". Go cannot. Rust is just an example.

Top of the hour again? Time for another Rust advertisement?

The topic at hand is about preventing library users from doing things the library author didn't intended using the type system, not "what happens if a language has zero-values". Perhaps you are not able to comprehend this because you are hungry? You're not you when you are hungry. Grab a Snickers.

what happens if a language has zero-values, is that you can't "parse, don't validate".

Maybe it's time for you to finally try rust? Or any other language without zero-values, since rust seems to irritate you in particular.

Don't worry, I have tried languages without zero-values. But they have nothing to do with the discussion that was taking place before the ad break. Now back to the show, you cannot prevent library consumers from doing things you don't intend without a compete type system. Rust does not have a complete type system. It leaves holes open for library consumers to do unexpected things and as such it has no relevance here. Sorry that your client's product isn't the be all and end all.

> Now back to the show,

The original claim was that with go, doing certain pattern "[...] guarantees that you can never forget to validate the username through any codepath". Which is not true. It is not true, because go has its own billion-dollar-mistake called zero values.

If you go way back there was talk about that, but the discussion had long shifted to "Sometimes it's nice to work with a type system where designers of libraries can actually prevent you from writing bugs."

I get it: You were in such a rush to fill your marketing quotas that you didn't bother to read the entire thread. Maybe the lesson here is don't use HN as an advertising platform next time? You should have known better from the get go.

You manage to present a strawman and produce a No True Scotsman fallacy all at once in this comment thread.

Nobody is suggesting that Coq should be used, so stop bringing it up (strawman). And yes, Coq might have an even stricter and more expressive type system than Rust. But nobody is asking for a perfect type system (no true Scotsman). People are asking to be able to prevent users of your library to provide illegal values. Rust (and Haskell and Scala and Typescript and ….) lets you do this just fine whereas Golang doesn’t.

And personally I would much rather have the compiler or IDE tell me I’m doing something wrong than having to read the docs in detail to understand all the footguns.

My personal opinion is that - even though I’m very productive with Golang and I enjoy using it - Golang has a piss poor type system, even with the addition of Generics.

> People are asking to be able to prevent users of your library to provide illegal values. [...] and Typescript

Typescript, you say?

   const bar: Foo = {} as Foo

Hmm. Oh, right, just don't hold it wrong. But "sometimes it's nice to work with a type system where designers of libraries can actually prevent you from writing bugs."

Your example doesn’t even satisfy the base case, let alone the general case. Get back to us when you have actually read the thread and can provide something on topic.

But that is not an accident, is it? It’s someone very deliberately casting an object. It’s not the same and you probably know it.

It might be an accident. Someone uninitiated may think that is how you are expected to initialize the value. A tool like Copilot may introduce it and go unnoticed.

But let's assume the programmer knows what they are doing and there is no code coming from any other source. When would said programmer write code that isn't deliberate? What is it about Go that you think makes them, an otherwise competent programmer, flail around haphazardly without any careful deliberation?

Reply on news.ycombinator.com