HypeScript: Simplified TypeScript type system in TypeScript's own type system

"Hello everybody out there using minix -

I'm doing a (free) operating system (just a hobby, won't be big and professional like gnu) for 386(486) AT clones. This has been brewing since april, and is starting to get ready. I'd like any feedback on things people like/dislike in minix, as my OS resembles it somewhat (same physical layout of the file-system (due to practical reasons) among other things)."

https://www.cs.cmu.edu/~awb/linux.history.html

I still use coffeescript over javascript because I feel like I can be as expressive as I want. I understand why most left for typescript (type safety), but I feel like everyone just gave up on reducing boilerplate for things in javascript. Switch statements, list comprehensions, array slicing, better equality operators... a lot of things that made coffeescript a great experience have never carried over.

Man, I know this wasn't really the intention of the comment, but I just read through that thread and got a little nostalgic. Crazy that was like 13 years ago. Sheesh.

Ah ah, another instance of "just a hobby, won't be big and professional like gnu".

Is that not referring to Coffeescript? I don't see the relevance.

TypeScript has a very limited form of dependent typing made available through `typeof`, but it does not have dependent typing as e.g. Idris does. However, in general, these sorts of demonstrations do nothing to show that a language can be dependently typed. These sorts of demonstrations show that a type system is Turing complete. However, a type system can be Turing complete without being dependent. For example, type-level integers might be completely different from run-time integers with no way to things from the latter to the former.

This linked project is very cool! I wonder if this path is expressly a non-goal of the TypeScript team though…?

In the context of type definitions, strings aren't really regular bare strings.

I.e. if I write

  type foo = {
     bar: "Vodka"
  }

This seems a little obscure and pointless, but you can put these string types in a union, and enforce that a value must be one of many values.

  function doTheThing(color: "RED" | "GREEN") {
      //do stuff
  }

  doTheThing("RED"); //ok
  doTheThing("GREEN"); //ok
  doTheThing("ORANGE"); //doesn't compile, because the type of the param *isn't* string, it's "RED" | "GREEN"

  type Mountain = { name: "EVEREST", height: 8848 } | { name: "K2", height: 8611 };

==============================================

For extra context - a lot of this is for interoptability with Javascript code - you want to call some Javascript function with a stringly typed enum, and enforce only passing in valid values, but the Javascript code still just deals with strings.

A lot of Typescripts kind of insane flexibility is so you can introduce type safety to all sorts of dynamic Javascript code, without having to make sacrifices on the dynamic-ness of it.

Turns out this flexibility is actually kinda awesome to have in general even when you're not trying to refactor an existing JS codebase.

As others have pointed out, they're not really "strings" per se, or at least can be a lot stricter than a string might seem when used right. We use that constantly for useful things.

The bigger reason why it is this way is to ensure you can write type annotations for stringly-typed Javascript. While Typescript is it's own thing really at this point, it still is very focused on making it possible to type-annotate JS code.

    type Event = 'onClick' | 'onHover'

    // some stringly typed javascript can now be nicely typed
    something.triggerEvent('onClick', someData)

I think it's kind of cool. It reminds me a bit of C++ templates, which are "compile time duck typed". The benefit is that you get lose typing constructs that are evaluated strictly and at type check time, which is kinda nutty. It means that you can lean really heavily on the compiler.

Sort of like using Python to generate Typescript, as random example - my Python code doesn't have to typecheck, but its output does, so I can do absurd shit in Python and still feel good about the output.

One example is something like this: https://www.typescriptlang.org/docs/handbook/2/template-lite...

These are types that are built from string templates. Since strings are loose and can be manipulated in crazy ways like appending, we can now manipulate types in the same way. We can write types that are themselves parsers.

So idk if that's good or not, the downside in C++ is that TMP errors are fucking insane, but the upside is that I can have a function that says "pass me something and I'll call "iter" on it and I don't care what that thing is".

It also feelsy kinda more "typey". Types are just values. Types are just strings or numbers or whatever. They're things, with the constraint being that they must exist concretely (or be inferrable) when the type checker runs. No distinction between types and values seems like it's the ideal.

  interface TypeScript {
    typeScript: TypeScript;
  }

Which article were you referring to?

The link in the post goes to a GitHub repo.

Tetris is challenging because TS escapes newlines in type output, so you'd end up with a bunch of\nwhich makes it\nhard to read the output. It could probably be done using arrays instead, but that gets truncated so you'd have to have a very small "screen"

I'd convince the team to switch to typed or get out of the project

Do everything you can to introduce TS incrementally. JSDoc simply isn’t enough.

Use TS locally

that sounds increasingly like a build-time macro system...

What complexity do you feel is unneeded?

> Please note that this project is meant to be used for fun and learning purposes and not for practical use.

There's no Javascript (or any other runtime) code in this at all. It all happens at compile-time.