[dvt]

You said a lot of stuff, and I disagree with most of it, but I'm open to dialogue.

> with almost no one in industry applying these lessons

Straight-up incorrect. Language designers think long and hard about how typings work in their languages. Rob Pike, Ken Thompson, and Russ Cox deliberated generics for like a decade[1] before finally allowing them in Go.

> a proper type system

I'm not sure exactly what you mean by "proper" -- but "rigid" type systems are extremely cumbersome to use practically. (Typed) λ-calculus is an academic example; Haskell is a real-world example.

> not too hard to retrofit dependent types (just don’t bother with Turing-incompleteness)

Hard disagree. It actually is extremely hard: type resolution is undecidable, for one. So you need to carefully design type resolution in a way that the "edges" of types don't (or can't) break the runtime too badly.

> why not go the extensible route of letting anyone hook into the “type checking” phase

Absolutely terrible idea, for many reasons, but mainly because, if C/C++ macros are any indication, people will abuse any kind of compile-time (or pre-processing) trickery you give them access to.

> write your own domain-specific checker, even

I guess I'm in the opposite camp here, I think domain specific languages are an absolute dumpster fire of abstraction and 99.9% of the time completely exceed the scope of the problem they're trying to solve. The purpose of a programming language is to be applicable to many classes of problems, and DSLs fly in the face of that pretty common-sense tenet.

[1] https://research.swtch.com/generic

[ebingdom]

> Straight-up incorrect. Language designers think long and hard about how typings work in their languages. Rob Pike, Ken Thompson, and Russ Cox deliberated generics for like a decade[1] before finally allowing them in Go.

I think that kind of proves their point. Parametric polymorphism is one of the most well-understood, least contentious extensions to the lambda calculus. It's formalized by System F and has been implemented in programming languages 40 years ago with great type inference for an important subset (Hindley-Milner). Yet generics was highly controversial in the Go community. And now since none of the standard library was designed with generics in mind, it's full of unsafe patterns that involve essentially dynamic typing (e.g., the `Value` method of `Context`).

Despite Rob Pike et al. designing one of the most popular languages today (Go), I consider them more experts in systems rather than programming languages.

> I'm not sure exactly what you mean by "proper" -- but "rigid" type systems are extremely cumbersome to use practically. (Typed) λ-calculus is an academic example; Haskell is a real-world example.

I find Haskell a joy to use, and I cringe at having to use languages like Java and Go, which are a minefield of error-prone programming patterns (like using products instead of sums to represent "result or error"). Generally speaking, my Haskell code is shorter, less buggy, and more reusable than my Go code, so I'm not sure what you mean by "cumbersome".

[obviouslynotme]

This is because type checking is the least impactful part of generics. As you said, that is a solved problem. The reason Go took so long thinking about generics has to do with their code generation. There are steep tradeoffs in compilation vs run time as well as compiler complexity and language complexity in general. Go's purpose was to be very fast to compile and run, born in a company where compile times for several projects run for hours even with massive parallelization.

There is very good reason that Go's initial compromise was to use built-ins for a small number of highly useful generics like arrays and maps.

[kaba0]

Java uses sum types for “result or error”. Exceptions just make it a language-level construct, with automatic addition of very useful stacktraces, auto-unwrap in the “result” case, etc.

[bitmapper]

Parametric polymorphism is even older than that! It's almost 60 years old, having originated in CPL.

[dvt]

> I find Haskell a joy to use, and I cringe at having to use languages like Java and Go, which are a minefield of error-prone programming patterns (like using products instead of sums to represent "result or error"). Generally speaking, my Haskell code is shorter, less buggy, and more reusable than my Go code, so I'm not sure what you mean by "cumbersome".

I just want you to realize that you are in the extreme minority here, but just from a common-sense POV, if I'm prototyping a project, looking for product-market fit, the last thing I want to care about is that my typeability is recursively enumerable or what-have-you. I just want to build something quickly without much hoopla (hence the massive popularity of very weakly-typed languages like JS and Python).

FWIW, I think that generics are a mistake in Go, but I was just trying to counter the point that language designers don't think long and hard about type-theoretic features. I think the main issue with generics, wasn't so much an inept "we don't know how to do this," but rather "is this worth the code complexity?" and "is this worth the added compile times?" -- both of which were main selling points of Go.

[ebingdom]

> I just want you to realize that you are in the extreme minority here

I'm in the minority because I've spent an unusual amount of time investing in my understanding of programming languages and their features, not because I have some fringe unjustified opinion.

> if I'm prototyping a project, looking for product-market fit, the last thing I want to care about is that my typeability is recursively enumerable or what-have-you.

With this comment you've lost your credibility in my mind. No one actually goes through this train of thought. I don't wonder about recursive enumerability whenever I start a project. I just use tools that help me build high quality software, such as principled static type systems.

[dvt]

> I'm in the minority because I've spent an unusual amount of time investing in my understanding of programming languages and their features, not because I have some fringe unjustified opinion.

I was just making a statement of fact. You're probably a very good programmer (as most type nerds, to coin a new term, tend to be), but still in the minority. Most programmers are not very good, and even good ones sometimes want to build things fast. (Where type ambiguity or even incorectness is accepted as a viable trade-off.)

This is why I stopped prototyping in Java, for example. JS just let me "do stuff" without thinking about it too hard. Lower code quality? Of course; but it let me try out more ideas in the same amount of time. Should you use JavaScript to write the operating system of a pacemaker? Probably not.

[novok]

IMO there is also 'culture' to various programming languages in their styles, standard libraries and so on. I think Java as language is actually fine, it's all the crap that surrounds it that makes it more unproductive or not. I find my self even once I get past 2000 lines that using something like python is less productive than a statically typed language.

[Zababa]

> I just want you to realize that you are in the extreme minority here

Considering how much people love and use Rust, Typescript and typechecking in Python, I don't think your point about people prefering JS and Python is that strong. There is one thing that's sure: people hate typing Car car = new Car(). var car = new Car()? That's already better. Python and JS got popular in reaction to Java/C#/C++, which were painful to use. Even Go now has type inference, which helps a lot. Now in 2022 it's not the same as 2005. You can have static types and a fast time to market. Before thinking about dynamic vs static, we should first try to see what the best dynamic and static typing schemes we can come up with.

> if I'm prototyping a project, looking for product-market fit, the last thing I want to care about is that my typeability is recursively enumerable or what-have-you

That's a bit of a strawman. If I'm prototyping a project, the last thing I want to care about is the weird API design that the author of that library I need came up with, instead of just implementing a common interface. Python and JS both have iterators for a reason. People in the functional world talk about monads all the time for a reason too: it's a general interface that allows you to write code fast. Nullable code is the same as async code, is the same as iteration (well, mapping) code, is the same as parsing code.

[dvt]

> Considering how much people love and use Rust, Typescript and typechecking in Python, I don't think your point about people prefering JS and Python is that strong.

I do think there's been a "type renaissance" in the past 5 or so years, after we all dove headfirst into JS and Python and broke the whole internet.

[Zababa]

Yeah, I agree. I think part of it is due to embracing better type systems. For example TS and Go are structurally typed, which was a rarity before. Type inference is everywhere now. Sum types are usable in Java, TS, Rust. All of these languages are better than 2005 Java. Maybe we'll have a comeback of dynamic languages in the next 5-15 years, and if that's the case I'd love to see what people will come up with.

[not2b]

C++11 is almost 11 years now, you no longer have to enter the type twice. Use auto to tell the compiler to infer the type.

[Zababa]

My whole point is that it wasn't feasible 12 years ago. Java 10 (which came with var) was released in 2018.

[youerbt]

> > just from a common-sense POV, if I'm prototyping a project, looking for product-market fit, the last thing I want to care about is that my typeability is recursively enumerable or what-have-you.

Then don't. It's not like Haskell forces you to, that's a myth about Haskell. You can get away with strings and integers everywhere if you so fancy.

There is just no common-sense in thinking that computer assisted programming is slower than unassisted.

[wlib]

I’m on my phone so I can’t really give this the response that it’s owed, but most of what I want to say is that I don’t think we disagree as much as you think. My mention of languages being the wrong approach to general programming is a key aspect of my position. You’re right that DSL’s are usually not a great idea, but that seems like more of an issue with the “syntax-chasing”. The affordances that a syntax forces upon everyone are why it takes a decade to add generics to Go and why macros are even used to begin with. As we see from the various notations used for equivalent math, we probably we be better off encoding the structure as a flexible semantics graph and then “projecting the syntax” however the programmer wants. Keep in mind that what I write is about possibilities more than what you would be forced to do every project. You wouldn’t expect everyone to import random type systems more than you would expect everyone of write and import their own random crypto system libraries. Some of the most popular languages out there have absolutely zero static checks. Would it be so bad to write a Turing complete static check function? Why do we care so much about decidability that we can’t even consider it in useful exceptions? Also, do you think macros a la lisp would be so bad if they had more powerful type systems backing them up and more flexible editors to understand them?

[dvt]

> Would it be so bad to write a Turing complete static check function?

I think most type systems are, in fact, Turing complete (there's a fun proof somewhere that TypeScript is, for example). And most typed languages (Go, C++, Java, TypeScript) have pretty mature static type-checkers, unless I'm misunderstanding your ask.

[creata]

"Typing is Hard" is a popular list of languages and the decidability of typechecking in them: https://3fx.ch/typing-is-hard.html

[sva_]

That's a nice list

> Zig

> undecidable, since evaluation of recursive functions at compile time is possible, thus requiring the compiler to solve the halting problem.

For some reason, I find that amusing.

[foobiekr]

Oh my goodness do I ever agree about any kind of “use parser cleverness to make your cute interior domain specific language” thing as found in Scala and Ruby and a few other contexts.

If you want a language, and have legit need, fire up antlr and build a quick compiler.

Parser cleverness if the “internal DSl” variety is on par with the C++ windowing libraries that used heavy operator overloading to be clever, the stuff like “window += new Button()” and other nonsense. Just awful and torturous.

[rowanG077]

Go is the poster boy for a language NOT learning anything from decades of PL theory and research.

[thaumasiotes]

In my mind, Go is an attempt at keeping the nice things about Java while discarding the worse things.

[kaba0]

Then they have a very strange definition of nice things, when it includes worse error-handling, more verbosity and bad abstractibility.