ATS-Postiats VS swift-corelibs-foundation

This is one of my two favorite books in The Little ...er series. The other is The Rational Schemer. These are two of the most advanced books in the series.

The Little Typer provides an introduction to dependent types. These can by used to guarantee things like "applying 'concat' to a list of length X and list of length Y returns a list of X+Y". It is also possible, to some extent, to use dependent types to replace proof tools like Coq. Two interesting languages using dependent types are:

- Idris. This is basically "strict Haskell plus dependent types": https://www.idris-lang.org/)

- ATS. This is a complex systems-level language with dependent types: http://www.ats-lang.org/

The Rational Schemer shows how to build a Prolog-like logic language as a Scheme library. This is a very good introduction to logic programming and the implementation of backtracking and unification is fascinating.

This is an excellent series overall, but these two books are especially good for people who are interested in unusual programming language designs. I don't expect dependent types or logic programming to become widely-used in the next couple generations of mainstream languages, but they're still fascinating.

Not being ATS

> any safety checks put into the competing language will have a runtime cost, which often is unacceptable

This is completely wrong. The best counterexample is probably ATS http://www.ats-lang.org which is compatible with C, yet also features dependent types (allowing us to prove arbitrary statements about our programs, and check them at compile time) and linear type (allowing us to precisely track resource usage; similar to Rust)

A good example is http://ats-lang.sourceforge.net/DOCUMENT/ATS2CAIRO/HTML/c36.... which uses the Cairo graphics library, and ends with the following:

> It may seem that using cairo functions in ATS is nearly identical to using them in C (modulo syntatical difference). However, what happens at the level of typechecking in ATS is far more sophisticated than in C. In particular, linear types are assigned to cairo objects (such as contexts, surfaces, patterns, font faces, etc.) in ATS to allow them to be tracked statically, that is, at compile-time, preventing potential mismanagement of such objects. For instance, if the following line:

      val () = cairo_surface_destroy (sf) // a type error if omitted

For a low level language in which you actually need to prove that your code doesn't cause UB, see http://www.ats-lang.org/

Here's the homepage fo the language: http://www.ats-lang.org/. The trick to finding results about with google is to search "ATS programming language".

In SPARK's case, you have to state your invariants in even greater precision than in Rust, and naturally it has worse inference. That's okay, the same happens in a certain language with Atrocious Type Syntax.

Yes, things like mentioned in the post can be expressed and checked statically, as demonstrated by languages like Idris and ATS. ATS might be even more relevant as it's an imperative language too, it can get rather low-level (like talking about properties of C runtime functions) while proving required properties statically, and it includes a solver for certain amount of arithmetics so that you don't need to prove obvious mathematical identities to the compiler. http://www.ats-lang.org/

a : https://github.com/apple/swift-corelibs-foundation/blob/main...

I wouldn't want to be the guy relying on this table advancement for this project. The fact that they're rewriting it in pure swift probably says a lot about the quality of the current approach.

b: makes absolutely no difference from a developer perspective. if you want to run threads in swift you're going to use gcd.

c: my take with all apple software tech has been to wait until they've dogfooded their own tech long enough to make it useable. Worked very well for me so far, thank you very much.

Correction: rewrite of PARTS of Foundation

There already was an open-source project to rewrite ALL of foundation, but it had stalled on the shores of having to re-implement everything:

  https://github.com/apple/swift-corelibs-foundation

The (shitty) old Linux implementation has been on GitHub for years.

Sigh... The traditional argument is that every dependency is of the same quality and trustworthiness of the language Standard Library.

If I use the SL, then I should also have no problem using some lashed-up chimera that has a dependency hierarchy that spans three continents.

Like I said, I'll do things my way.

For the record, here's a peek at some of the "worthless" packages that I use in my own work: https://github.com/RiftValleySoftware

Also, for the record, here's the Swift Foundation Library: https://github.com/apple/swift-corelibs-foundation

It has plenty of open issues: https://github.com/apple/swift-corelibs-foundation/issues

If every dependency chain can match these, yhen I'll be open to considering them.

As it is, I do use the occasional external package, but I'm picky.

CoreFoundation is (partially?) open-source and cross-platform now: https://github.com/apple/swift-corelibs-foundation

Partly this is doable because although RFC 2616 specifies a max URL length of 2048 bytes, most browsers allow much longer, with Chrome and Firefox allowing at least 64k chars (that's what they'll display but it seems like more is happily processed), while Safari allows URL strings up to 2GB in size[1]!

[1] https://github.com/apple/swift-corelibs-foundation/blob/b23d...

Regarding your point #3, Swift does indeed have an open-source cross-platform implementation of Foundation. swift-corelibs-foundation

Foundation is open source and (mostly) works on Linux. What else do you want to see “opened up?”

Foundation is not the standard library of Swift. Swift has its own standard library that is bundled with the language on all platforms that are supported.

And Foundation itself isn't written in Swift, a good portion is written in C.

> A significant portion of the implementation of Foundation on Apple platforms is provided by another framework called CoreFoundation (a.k.a. CF). CF is written primarily in C and is very portable. Therefore we have chosen to use it for the internal implementation of Swift Foundation where possible. As CF is present on all platforms, we can use it to provide a common implementation everywhere.

https://github.com/apple/swift-corelibs-foundation/blob/main...