The issue with that is that making tuples a local-only construct is not trivial. A run-of-the-mill tuple is a data type that fits in the type system quite well, it's not costly to create. But a tuple that can only be used locally requires to make a special case in the compiler, and to check it everywhere.

Besides, you may end up with divergences in your community about how local a tuple should be allowed to be. Can it be passed to a lambda? Can you map over it in a local context? etc. Overall, deciding where tuples should be used is an easy choice for the developer, and a very hard choice for the language creator.

Making the names part of the type solves this, like structural object types in TypeScript. I’ve come to the conclusion myself that, with the right language syntax supporting it, positional arguments and tuples should be limited to two, maybe three entries, and in the vast majority of cases should be replaced with named/keyword arguments and records even when they are that small (with unnamed, ordered entries being used in cases where there aren’t better names than “first” and “second” or “a” and “b”).

If developers used tuples wisely we wouldn't be having this conversation. That's the primary reason why Java has no tuples.

Is there any good writing on overuse of tuples? Up until this thread, I just always thought that was a pet peeve of mine.

Internally I've tried to make the case that nobody understands the reason a tuple exists except the person who wrote it, and a discriminating union, record, or variant is always a better choice if you're optimizing for the common case (that is, readability).

The industry is balkanized on it. Functional languages which tend to model closed systems, with strict types, and hence easier ad-hoc refactoring swear by tuples. OOP platforms which deal with the "outside world" a lot and so need stable API that can evolve without BC breaks avoid tuples.

Notice also web APIs virtually never use tuples (everything is objects with named fields both in complex input and virtually all output).

A language that targets the browser is going to be inherently open. It has to deal with browser DOM, it has to deal with service APIs, it also has to potentially interact with JS libraries.

It'll be an uphill struggle to apply Ocaml style in it.

> Functional languages which tend to model closed systems [...] OOP platforms which deal with the "outside world" a lot

The open vs closed systems logic simply doesn't have any kind of relation with whether one "deals with the outside world", it's about knowing what you're about to receive. And Java, which you quoted earlier, is very much geared for closed systems. On the other hand, Prolog, a language that hardly qualifies as OOP is built to work on open systems.

Closed systems language deal with the outside world pretty gracefully, by parsing their inputs.

> A language that targets the browser is going to be inherently open.

There's been a flurry of closed-system languages for the web in the last decade (e.g. Elm, Fable, etc.), and they work just fine.

You fail to account for change, and time.

As functional languages often do. /s

Tuples have coupling order. That's a fact. So if you have tuple [a, b, c, d], then you can maybe extend this by adding ...e, f] at the end, if your parser can ignore extraneous items.

But even if your parser can do that, you still can't remove b without BC breaks, because then the rest get shifted, and you have a mess.

This is not a problem when the tuple exists only in the confines of some singular unit of code, that gets refactored together. But if it escapes, you have a problem. Because over time, you'll want to change this tuple, and you can't refactor the entire world at once (which is more often than not the issue of functional programming and why it can't scale well).

You seem to believe that, because tuples are available in a language, they will be used everywhere. And indeed, that wouldn't be great.

From my mileage in this industry, though, the cases you describe simply don't happen. As you said, tuples aren't used in interfaces, because developers know better than to do that.

> which is more often than not the issue of functional programming and why it can't scale well

I don't know what you've done with FP, but in your last few posts, you've been making claims about it that simply don't match my experience. There's not much to discuss without specifics, though, so maybe you could expand about the cases where you had issues with it?

I wish tuples didn't exist in interfaces, unfortunately every function and method argument list is one. /s

I appreciate your point that people try and avoid tuples where not appropriate, but the question is why even have that opportunity, when we can nudge the community to use equivalent "named attribute tuples".

Regarding scale, FP scales great for certain types of problems. But it's not great at modeling or encouraging boundaries. Imagine doing FP where all your types cease to exist for part of your codebase, but also you need to interact with the code where the types are. Even more, imagine if those two modules may fail independently (i.e. so you lose one of them). Anyway I think I'm becoming too abstract.

Basically the FP world needs to be more like Erlang. Erlang is functional but keeps units bounded (in processes).

> but the question is why even have that opportunity

I have provided a valuable use case above, and creating a structure allowing convenient use cases while preventing inconvenient ones would be extremely costly.

> But it's not great at modeling or encouraging boundaries.

What features are you missing specifically? You cited the need to "keep units bounded", but most FP langs provide the ability to contain implementation details within modules, by not exporting them.

> Imagine doing FP where all your types cease to exist for part of your codebase, but also you need to interact with the code where the types are. Even more, imagine if those two modules may fail independently (i.e. so you lose one of them).

I've had to deal with antiquated DBs containing unreliable data using flaky drivers, and while working with legacy can be painful sometimes, the FP paradigm caused no specific trouble.

Yes, Java has a proliferation of Pair classes instead, along with people arguing against them.