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Sweetjs is unfortunately dead [0] for like 5 years now.
It also doesn't have any typescript awareness which is required to build this kind of functionality - you want to have static type introspection available in macros so you can generate code based on provided types.
[0] https://github.com/sweet-js/sweet-core/graphs/contributors
Compared to a struct in C, Rust, or Golang it takes more typing on behalf of the programmer and only works in a narrowly specific set of circumstances.
Convenient in some ways (e.g. if you only are comfortable in JS), and does nothing for other contexts.
https://swagger.io/
Is this more than a subset of Wordnik's Swagger?
This looks really nice as an alternative to JSON schema, which is horribly verbose. Like using RELAX NG compact syntax for XML schemas back in the day, versus horrible verbose DTDs or XSDs.
But I think the most natural way to express JSON schemas would be TypeScript type declarations. Is there a project that can take a TS type and generate a runtime parser/validator for it?
I thought maybe Quicktype (https://quicktype.io/) was that, but it looks like it only takes JSON as input, not TS types.
YES! I've introduced ts-to-zod into my codebase only yesterday, and it's served my needs exactly. It doesn't handle generics or mapped types, but that's a fair price to pay.
It also works the other way, you can define a zod schema and you can infer types for your data from it.
https://github.com/fabien0102/ts-to-zod
After some frustration with the TypeScript schema library ecosystem, I've decided that I'd prefer to declare my types using TypeScript's excellent type syntax, so I can take advantage of generics, mapped types, etc. Then, I'll take those TypeScript types and compile them to whatever alternative schema format I need.
There are many libraries that claim to convert your Typescript types to other formats, such as ts-json-schema-generator, ts-to-zod, or typeconv/core-types-ts. These libraries work by interpreting the Typescript AST, essentially re-implementing a bare-bones type system from scratch. Most do not support advanced Typescript features like generic application, mapped types, or string literal types. So, what's the point? To avoid those limitations, I use Typescript's first-party ts.TypeChecker API to analyze types, and an existing library called ts-simple-type (which I've forked) to convert from ts.Type to a more usable intermediate format. Then, I recurse over the intermediate format and emit "AST nodes". It's pretty simple, but seems promising.
So far, I have compilers from TypeScript type to Python 3 and Thrift. But I plan to add OpenAPI/JSONSchema, Protobuf (Proto3), Kotlin, Swift, and maybe Zod and Avro. Each target language is around ~300 LoC so they're pretty easy to put together.
Repo: https://github.com/justjake/ts-simple-type
Compiler input and output: https://github.com/justjake/ts-simple-type/blob/jake--compil...
Thrift compiler: https://github.com/justjake/ts-simple-type/blob/jake--compil...
Python compiler: https://github.com/justjake/ts-simple-type/blob/jake--compil...
```
The main thing we're using it for now, is defining an OpenAPI schema and using the types in the front-end and backend, and using the schema to validate requests and responses, both client-side as well as server-side. Validation is done using avj [1].
We used Joi before and want to replace that code with JSON Schema, but that is quite the hassle. I like that TypeBox uses JSON Schema underneath, so migrating to another library should be easy.
[0] https://github.com/sinclairzx81/typebox
Deepkit is quite interesting in this area: https://deepkit.io/
It reimplements the type system as… a stack based VM that expands the TS typedefs if needed at runtime?
I would use it if the risk factor wasn’t so high. I’m too scared of needing to maintain their crazy cool stuff to use it.
I would love Microsoft to build those APIs first party and officially support them.