[sankha93]

Hey, nice work with Sorbet! I am one of the grad students who worked on RDL, one of the early research projects related to Ruby type systems. What are the next set of challenges that a tool like Sorbet needs to solve? I see you mentioned meta-programming in the blog post, is that something that is handled well by Sorbet? Sorry if this is already handled, I haven't been up to date with the latest features of Sorbet.

[jez]

Thanks for your work on RDL! The post didn't mention it, but Sorbet still owes most of its type definitions for the Ruby standard library to RDL's original annotations. We just borrowed them and changed the syntax.

Our general approach to metaprogramming at the moment has been two-fold:

- Use ahead-of-time code generation powered either by runtime reflection or ad-hoc static analysis to generate RBI files declaring things that have been metaprogrammed. - Build type system features, errors, and autocorrects that encourage people to structure their code in ways that doesn't require metaprogramming to solve.

Metaprogramming is definitely still a sticking point, but the existing solutions work ~okay and the rest of the upside Sorbet provides make it worthwile to power through.

Next challenges:

- Make it faster. While the post was talking about how fast it is, it wasn't telling the whole truth. Turns out some type checking operations in a 15 million line codebase are still slow, and we're working on making those faster.

- Add more IDE features. At the beginning of this year I put a lot of work into making Sorbet's parser more tolerant of syntax errors, which helps things like autocompletion work better. We also want to make more code actions, autocorrects, and refactoring tools, to bring Ruby in line with what you'd expect from other typed languages in the IDE experience

- Add more type system features. Shapes and tuples are a huge unimplemented feature still, and people ask about it all the time. There are a handful of other type system features (happy to list them if you're curious) that would also let people write idiomatic Ruby and still have good typing.

Lots left to do!

[mwint]

I write a lot of Ruby for work, but I’m not sure what “shapes” are - do you have any good reference where I could start reading?

[jez]

They're basically Hash literal types in Ruby. It's what TypeScript calls object types:

https://www.typescriptlang.org/docs/handbook/2/objects.html

(Ruby and JavaScript mean slightly different things by the word "object" so we chose a different word.)

Flow also has a distinction between exact and inexact object types:

https://flow.org/en/docs/types/objects/

where the difference is whether other, unspecified fields are allowed to hide in the object, or whether values of type `{foo: number}` must have only the `foo` field, and no other fields.

[girvo]

Shapes and tuples will be huge. I use them constantly in the languages that support them!