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TypeScript please give us reflection/runtime types

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Re: TypeScript please give us reflection/runtime types

#31

Post by dimitrios1 »

random_mutex wrote: post #22
andix wrote: post #5

There is a good reason for not doing this. Typescript would become some kind of runtime on top of JavaScript. A new language that compiles to JavaScript. Currently TS is only JavaScript with type annotations. There are many languages that compile to JavaScript. Pick one of them and use it! And I have the feeling, that people who want runtime typed Typescript would rather like to write Java/OOP style code instead of J…

ReasonML

ReasonML suffered tremendously when the community split and went off to do ReScript. I don't think either have recovered the original luster.

Re: TypeScript please give us reflection/runtime types

#33

Post by Eric_WVGG »

thanksgiving wrote: post #29

I’m not an expert or anything but I sincerely feel like this is barking up the wrong tree. To anyone who works on typescript/JavaScript outside the context of a web browser, you DO NOT matter as far as I am concerned. If I was in control of JavaScript/typescript, I’d give zero attention to your demands. You are not my top priority. Go away. I feel like we are losing focus here. Should JavaScript be an all purpose lan…

I don't understand this comment at all. I mostly work on client-side front-end and am absolutely desperate for better type generation. Zod is making me want to jump out a window right now.

Re: TypeScript please give us reflection/runtime types

#34

Post by PaulHoule »

a_wild_dandan wrote: post #24
andix wrote: post #5

There is a good reason for not doing this. Typescript would become some kind of runtime on top of JavaScript. A new language that compiles to JavaScript. Currently TS is only JavaScript with type annotations. There are many languages that compile to JavaScript. Pick one of them and use it! And I have the feeling, that people who want runtime typed Typescript would rather like to write Java/OOP style code instead of J…

I'm misunderstanding your reasoning here. TS is already a new (superset) language which compiles to JS. Runtime types solve the problem of maintaining two duplicate, separate type systems -- one for compilation, one for validating data. I'm not seeing how that's related to OOP. For instance, my preferred workaround lib for this problem, `io-ts`, leans hard on functional programming.

Yeah but just because types exist at compile time doesn't mean they exist at run time.

For instance with Generics in Java a List is the same as a List at run time, the compiler can enforce rules that let you add a String to one but not add a String to the other but the runtime has no idea. This has various negative consequences but it also let them retrofit generic collections on top of the old collection implementation in Java unlike the disaster in .NET where both had to coexist for years.

Similarly C compiles to machine code and in machine code there are just memory locations and registers, types are implicit in how you use those things but not spelled out explicitly. C++ does have RTTI but is one of the many open pits, like Exceptions, in C++.

Typescript types are the same way, once the compiler has done its type checking you know the code is going to behave according to the type system even if the types have been "erased".

Re: TypeScript please give us reflection/runtime types

#35

Post by Quekid5 »

a_wild_dandan wrote: post #24
andix wrote: post #5

There is a good reason for not doing this. Typescript would become some kind of runtime on top of JavaScript. A new language that compiles to JavaScript. Currently TS is only JavaScript with type annotations. There are many languages that compile to JavaScript. Pick one of them and use it! And I have the feeling, that people who want runtime typed Typescript would rather like to write Java/OOP style code instead of J…

I'm misunderstanding your reasoning here. TS is already a new (superset) language which compiles to JS. Runtime types solve the problem of maintaining two duplicate, separate type systems -- one for compilation, one for validating data. I'm not seeing how that's related to OOP. For instance, my preferred workaround lib for this problem, `io-ts`, leans hard on functional programming.

> TS is already a new (superset) language which compiles to JS.

Yes, but also no. The point is that it doesn't really add more semantics over plain JS. You can erase all the type annotations (well, replace with "any") and it'll do the same thing if you ignore the type checking.

If there's any "transformation" from TS to different-looking JS[0], it's mostly just syntactic embellishment (think LISP macros and such), not semantic.

[0] Not sure if there is, tbh

Re: TypeScript please give us reflection/runtime types

#36

Post by zoogeny »

This is the perennial problem with language design. Everyone wants something and they even have reasonable grounds to ask for it.

I myself have come across moments where some rtti/reflection would have been useful. In those cases I was often able to use branded types. Having something like that built into the language might be nice. But I'd also support TypeScript and JavaScript developers making the choice not to support it ever. IME, working around rtti type code often forces the programmer to come up with a much better approach.

Re: TypeScript please give us reflection/runtime types

#37

Post by decs »

rcme wrote: post #4

There are good typed deserialization libraries. Personally, I prefer runtypes but there are options.

Agree, zod, arktype, and typia are impressively easy to use! Though, I feel that this environment created a different problem of spreading developers into multiple solutions. So for lib devs like me, we end up having to choose between coupling with a single validation lib or managing support for multiple (like tRPC does). To address that, I ended up doing a reusable lightweight lib that wraps that logic for supporting multiple: https://typeschema.com

Re: TypeScript please give us reflection/runtime types

#38

Post by Waterluvian »

moystard wrote: post #30
andix wrote: post #20

Earlier quoted context omitted.

And that's one of the features of typescript that really sucks. String union types work so much better.

Why does typescript enum really suck?

There’s a ton written about this if you search for “typescript enums.”

I just finished removing them from a major project. Here’s a few of my personal notes:

1. They don’t play well with duck typing. (Eg. show me a subset of an enum)

2. They require an import every time you want to utilize them.

3. They are pretty wordy compared to union strings.

4. Their string value version encourages misuse as a key-value pair.

5. Unless you use the string value version, they suck to debug because logs just show 0,1,2,3.

Re: TypeScript please give us reflection/runtime types

#39

Post by JohnDotAwesome »

Instead of pleading to the TypeScript gods, why not make a deal with the JavaScript deities? Let's get type-checking into JS!

If I want runtime types, I reach for type guards. If I need to do this a lot, then I reach for io-ts or zod and pretty much exclusively write types as validators/codecs/schemas or what-have-you.

I don't think TS - as a specification, type-checker, community, or otherwise - needs to concern itself with runtime validation UNLESS JS gets some agreed upon way to do it.

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