Migrate to TypeScript

[recmo]

There typescript typeings for solidity-parser-antlr and prettier.

I'm currently improving the AST typings to the point where most of the grammar rules are checked at compile time. With this you can write code transforms that don't corrupt the AST.

It also helps to track changes in the grammar over time. As the Solidity syntax evolves, the new typings will show where the printer and transforms need to be changed.

Finally it allows us to use more modern features of JS like lambda functions safely. Functional programming features are very useful for language processing.

[mattiaerre]

thanks for starting this conversation @recmo it'd be a cool idea to explore; what others think about this? how difficult would be to practically do the migration? if you have time to attempt a PR that would be awesome!

// cc @fvictorio @federicobond @j-f1

[fvictorio]

I've never worked with typescript, but I can see how static typing would be very useful here.

[mattiaerre]

totally down to take the ownership of this issue after the beta launch then!

[mattiaerre]

some useful resources:

• https://www.typescriptlang.org/docs/handbook/migrating-from-javascript.html

• https://gist.github.com/OliverJAsh/13b5410843d6bee692927897f0c84197 (very interesting post)

• https://basarat.gitbooks.io/typescript/docs/types/migrating.html (and very good gitbook in general)

[federicobond]

I’ve worked with Typescript recently and I can only say good things about it. It will definitely be my default choice from now on in any Node/front-end project.

[mattiaerre]

do we think doing this is still worth it? how big of a change having TS support would be? // cc @fvictorio @Janther

[fvictorio]

It's probably worth it. I migrated the parser to typescript recently, but I'm not 100% happy with its output yet. Maybe when it's in a good state we can consider migrating here. (I'm also ok with keeping it in js, anyway.)

[Janther]

I believe we will need the types from the parser first as well.
I do believe that there will be an improvement in the code, although the work on this project regarding testing, coverage, and code architecture is already on a good level for understanding the project (we might need some comments here and there).

[mattiaerre]

ok, let's keep it open for now and we'll revisit it soon

[fvictorio]

Copying something I wrote on our internal chat here:

---

Before working on this, it would be nice to check how good prettier's support itself is for typescript. For example, right now we have functions like this:

const Block = {
  print: ({ node, options, path, print }) => {
    // ...
  }
};

That will surely not be typed automatically, but how hard is it to manually annotate the types here? What happens with things like path.call(print, 'trueExpression')? Will the trueExpression part be verified by typescript? That depends a lot on how prettier types are done.

I think the next step in a (potential) migration to typescript would be to answer those questions.

[sambacha]

fwiw airbnb has a tool for automating (YMMV) javascript to typescript: https://github.com/airbnb/ts-migrate

at worst it will show you how much effort you have ahead of you

[mattiaerre]

Thanks, @sambacha if you like to give it a try and see how it goes, please by any means be our guest 🙏