> Then why do you think nobody uses them (outside of certain narrow tasks)? It is hard to deny the results.

> The reality is that they are intractable. For the vast majority of programming problems, testing is good enough and far, far more practical. There is a very good reason why the languages people normally use (yes, including C# and Rust) prefer testing over types.

Deny what results? Do you have some kind of formal demonstration that they are impossible to use outside of those "certain narrow tasks" (unknown)? Or do you have proof that NOBODY use them for more than those "certain narrow tasks"? Otherwise this is more "I feel like it" than something I would even need to justify deeply.

Also, with Rust this is certainly false, most people that I've saw using it (and myself) don't overly test everything in it besides more complex behavior (which types hardly can prove it is correct), but it eliminates the need for a whole suit of smaller tests that would be necessary in less powerful languages (it is literally regarded as one of the languages where "if it compiles, it works" -- or "generally works" for a reason).

> Incidentally, but not explicitly. You also end up incidentally testing things like the shape even in languages that provide strict guarantees in the type system. That's the nature of testing.

Now I want some proof to it. Make an example test that "incidentally tests things like the shape" in C#, please. I've seen a good bunch of codebases in C# and I'm pretty sure I never saw something even remotely like this.

> I do agree that testing is not well understood by a lot of developers. There are for sure developers who think that explicitly testing for, say, the shape of data is a test that needs to be written. A lot of developers straight up don't know what makes for a useful test. We'd do well to help them better understand testing, but I'm not sure "don't even think about it, you've got a half-assed type system to lean on!" get us there. Quite the opposite.

Now this point is getting lost, you changed from:

> At some point you start to notice that your tests end up covering all the same cases as your advanced types, and you begin question why you are putting in so much work repeating yourself, which ultimately sees you want to look for better.

To "I know better than a lot of developers how to test", which don't make any sense to me. You either has the same baseline testing knowledge of this "lot of developers", and hence reach similar conclusions in regards to testing (what I quoted), or you have a better understanding of it than them (and your conclusions are merely based on your own perception of testing). I don't think those points are free to take, you would need to justify this a little bit more, and I'm sure """don't even think about it, you've got a half-assed type system to lean on!""" was not the core of my point, nor a faithful representation of what I said.

> Well, they're not. And they are not going to without some fundamental breakthrough that changes the tractability of using languages with an advanced (on the full spectrum, not relative to Go) type system. The tradeoffs just aren't worth it in nearly every case. So we're stuck with half-assed type systems and relying on testing, for better or worse. Yes, that includes C# and Rust.

I would not call Rust's type system 'half-assed' tho, it is very compatible with a bunch of ML languages, it is really a very sophisticated type system with HM type inference, generic associated types, traits and more powerful things. Comparing it to C# would be unreasonable. I may also be a little bit mean to C#, it has a "mid-tier, but sufficiently good type system" for many purposes, my main problems with it are regarding to the type inference (and the lack of some basic features), but it has generics since early versions, it has interfaces, classes, subtyping, recursive type constraints, extension methods, deterministic destructors, scoped local definitions and a bunch of small useful resources. It is surely mid-tier in many aspects, but not something trivial and I don't think you can put them all in the same basket.
Either way, I also don't think that you got my point: I said it matters more that the right people are using them, precisely because those are the people that would make good use of those type systems. As a very simple example (and I consider Rust type system a very powerful one in this context) it was interesting to see that someone like Asahi Lina said the Rust language and it's features were useful for making a GPU driver, that she experienced less problems common in C (a language with a way smaller and simpler type system) and that it was having some positive effects on it. Surely, most software is not written in Rust, but the ones that are, and this is what matters, are being developed by the right people that would use them right. This is another point, as I stated earlier, but you responded to it so I'm giving a better exploration on the surroundings of what I meant here.

> Does it matter? Engineers don't make decisions based on some random emotional plea on HN. A keyboard cowboy might be swayed in the wrong direction by such, but then this boils down to being effectively equivalent to "If we don't talk about sex maybe teenage pregnancy will cease." Is that really the angle you want to go with?

It absolutely does matter. And I do believe we should talk less about mundane things and that glorifying bad ways of living can have a terrible influence in teenage brains (and even in adults in many cases), but this is also another discussion. My point is that people don't argue emotionally like they were arguing emotionally, they argue emotionally like they were right. They are (generally) not saying "well, see, I really love Go and its simplicity, so because of my personal preferences I'm saying that other languages are bad", they are saying "see, as we obviously values simplicity, and Go is simpler than that X language, Go is better than X language" (which is the shape of arguments I usually see, not ipsis literis, but in implications and the style of pointing things), and this is much more dangerous than any "purely emotional plea" (and also, most software engineers are not masters of argumentation that can dissect something like this and find all the intricate problems and possible fallacies behind it, they will believe what is most believable at the moment for them and that's generally it).