genType VS proposal-type-annotations

I don't really use ts-belt to be certain, but by looking at the source, it seems that it's using genType, which can generate TS types from ReScript values, and that makes interop work really well.

They discuss this in their docs.

https://rescript-lang.org/docs/manual/latest/introduction#di...

Seems like a type system for Javascript, built with a differing set of opinions than Typescript.

Looks like they also offer some form of TS interop:

https://rescript-lang.org/docs/gentype/latest/introduction

TS Belt has been built with ReScript (and its Belt stdlib). ReScript generates highly performant JavaScript code, and with genType it also automatically generates TypeScript types. Moreover, I've added a few codemods to the building process to provide even more code optimizations and cleaner TypeScript signatures.

To interoperate with TypeScript with proper type information you’ll use third-party genType. Add it as a devDependency and annotate the module export you want to generate with @genType (in previous versions you’d surround annotations with square brackets).

That proposal is not fully compatible with Typescript: https://github.com/tc39/proposal-type-annotations?tab=readme...

They held a meeting a few months ago so it's alive but probably still years away.

https://github.com/tc39/proposal-type-annotations/issues/184

I particularly like this thread in the TC39 types proposal. TypeScript IS a development trojan horse and locks you into the Microsoft Way of being a JS developer.

Edit: There is a proposal to extend JavaScript with type annotations, which would allow ("a reasonably large subset") of TypeScript to run directly in the browser. Yay!

https://github.com/tc39/proposal-type-annotations

More importantly, TypeScript typically commits to build things into itself when the proposal in JavaScript reaches Stage 3. The pattern matching proposal in JavaScript is Stage 1, but depends on many other proposals as well that may or may not need to be at Stage 3 as well for it to work. This particular proposal is interested on pattern matching on JavaScript Objects and other primitives, just like Python does with it’s native primitives. These are also dynamic types which helps in some areas, but makes it harder than others. Additionally, the JavaScript type annotations proposal needs to possibly account for this. So it’s going to be awhile. Like many years.

this is exactly what I want from the _Types as Comments_ proposal[0] as I think it's the only way that types can feasibly become part of the language. It's hard to imagine how all of the concepts TS introduces via special syntax can be covered otherwise.

[0] https://tc39.es/proposal-type-annotations

Crossing my fingers that the proposal for allowing (browser-ignored) type annotations in javascript progresses: https://tc39.es/proposal-type-annotations/

Between that, HTTP2/3 and ES modules many of the downsides for building apps with no compile step are almost completely mitigated.

JSDoc can get you pretty far, but it can be clumsy sometimes. There’s a [TC39 proposal](https://github.com/tc39/proposal-type-annotations) to allow types to live in JS code and be treated as comments (similar with Python types today)