TypeProf for IDE: Enrich Development Experience without Annotations

RubyKaigi Takeout 2021

https://rubykaigi.org/2021-takeout/presentations/mametter.html

Transcript

1. TypeProf for IDE: Enrich Development Experience without Annotations Yusuke Endoh (@mametter) RubyKaigi Takeout 2021
2. Yusuke Endoh / @mametter •A Ruby committer working at Cookpad w/ @ko1 • TypeProf: A static type analyzer for Ruby 3 •An esoteric Ruby programmer • See my RubyKaigi bio 2
3. A recent contribution: error_highlight 3 json = { foo: { bar: { baz: 42 } } } json[:foo][:barr][:baz] # Ruby 3.0 $ ruby t.rb t.rb:2:in `<main>': undefined method `[]' for nil:NilClass (NoMethodError) # Ruby 3.1 $ ruby t.rb t.rb:2:in `<main>': undefined method `[]' for nil:NilClass (NoMethodError) json[:foo][:barr][:baz] ^^^^^^ Credit: The original author of its prototype is @yui-knk https://github.com/ruby/ruby/pull/4470
4. "I love static typing" … or do you? •Static typing is a means, not an end •The end is the modern development experience • Demo: TypeScript 4
5. The modern development experience with TypeScript 5 On-the-fly error reporting
6. The modern development experience with TypeScript 6 On-the-fly type inference
7. The modern development experience with TypeScript 7 Go to definition
8. The modern development experience with TypeScript 8 •Completion Completion
9. The modern development experience with TypeScript 9 Hint for arguments
10. "I love static typing" … or do you? •Static typing is a means, not an end • The end is the modern development experience • On-the-fly error reporting, go-to-definition, completion, argument hint, etc. •Q: Isn't it possible to achieve the experience without changing the Ruby language? • My answer is "Possible!" 10 (under some conditions)
11. Today's topic: TypeProf for IDE •A VSCode extension for Ruby • Powered by TypeProf (a static type analyzer for Ruby) •Demo 11
12. The modern development experience with TypeProf for IDE 12 On-the-fly method signature
13. The modern development experience with TypeProf for IDE 13 On-the-fly error reporting
14. The modern development experience with TypeProf for IDE 14
15. The modern development experience with TypeProf for IDE 15 On-the-fly type inference Completion
16. The modern development experience with TypeProf for IDE 16 Hint for arguments
17. Demo: Summary •The modern development experience is possible without full type annotations by TypeProf for IDE 17
18. Agenda ➔ Recap: Types for Ruby 3  •TypeProf • TypeProf for IDE • Conclusion 18
19. Recap: Types for Ruby 3 19 Name What RBS TypeProf Steep Sorbet The Ruby official type definition language A static type analyzer for Ruby A static type analyzer for Ruby A static type analyzer for Ruby
20. RBS: Ruby official type definition language 20 class User def initialize: (String) -> void def name: () -> String end
21. What a static type analyzer does •Infers the types of a given program • Reports a potential runtime type error • Supports IDE 21 msg = "Hello, " + user.name msg: String msg = "Hello, " + user.naame Error!
22. Differences of each static analyzer 22 Type inference Error reporting IDE support Analysis speed TypeProf 🙂Strong ☹️Weak No → Yes ☹️Slow Steep ☹️Weak 🙂Strong Yes 🙂Fast
23. Agenda •Recap: Types for Ruby 3 ➔ TypeProf  • TypeProf for IDE • Conclusion 23
24. The key idea of TypeProf Runs a Ruby code in "type-level" Traditional interpreter def foo(n) n.to_s end foo(42) Calls w/ 42 Returns "42" TypeProf def foo(n) n.to_s end foo(42) Calls w/ Integer Returns String Object#foo :: (Integer) -> String 24
25. The user-facing feature of TypeProf •Ruby 3.0 • A type inference tool to create a prototype of RBS • No IDE support • Ruby 3.1~ • + IDE support! 25
26. Demo (memo) •Test instead of type annotations •Passing an unknown type • Manual RBS specification • Flow-sensitive analysis • Manual overloading •Block, RBSWiki example 26
27. Demo: Tests instead of type annotations 27 untyped String
28. Demo: Passing an unknown type 28 The method signature is changed to accept a new type Error in the callee side
29. Demo: Manual RBS specification 29 Click here A prototype RBS is created
30. Demo: Manual RBS specification (cont'd) 30 Error in the caller side # means RBS-defined
31. Demo: Flow-sensitive analysis 31 No error type case
32. Demo: Manual overloading 32 No error Write RBS for overloading Argument hint is selectable
33. Demo: Block 33
34. Demo: Works with a simple Rack app 34
35. Agenda •Recap: Types for Ruby 3 •TypeProf ➔TypeProf for IDE • Conclusion 35
36. Language Server Protocol (LSP) 36 LSP client (vscode) LSP server (TypeProf for IDE) code changed error found complete "5.ti" maybe "5.times" 5.ti| Do you mean: 5.times 1 + "str" 1 + "str" Is this a bug?
37. Currently supported LSP features •Show method signatures •Show potential errors • Go to definition of methods/variables • Find references of methods/variables • Completion •Show hint about method arguments 37
38. Not-implemented-yet LSP Features 38 Type hover Documentation • More challenging features • Auto refactoring (renaming), quick fix suggestion, etc. • Contribution is welcome!!!
39. Future work: the parser needs more ♥ •An AST node knows only the beginning and end of the source code • The parser returns nothing when syntax is broken • Cannot complete an incomplete call 39 current implementation desired behavior foo(k:)
40. About analysis performance •TypeProf is very slow • It traces "require 'foo'" (even if it is a gem) •TypeProf for IDE stops the analysis in one second • Nothing will be reported where it couldn't analyze within the time limit 40
41. How to make TypeProf fast •Write RBS for gems • so that TypeProf don't have to analyze gem sources • Watch pocke's talk (Day 2) • Divide your application to components • and write RBS against their interfaces • We need experiment with a practical use case 41
42. Agenda •Recap: Types for Ruby 3 •TypeProf • TypeProf for IDE • Implementation ➔Conclusion 42
43. Release plan •TypeProf for IDE will be released in Ruby 3.1 • Happy if you could play with it and give us feedback • How to run the development version https://gist.github.com/mame/86234de6a58352b9f994e0f8a6d6fbc2 (in Japanese) •Ready for production? • Experimental, but hopefully works for small programs • For large code base, please write RBS for gems first! 43
44. Special thanks •Hideki Miura • Ruby committers: matz, akr, ko1, soutaro • Katsuhiro Ueno & Eijiro Sumii •Stripe team & Shopify team & Jeff Foster • Yuta Saito (@kateinoigakukun) • Many improvements of TypeProf for IDE 44
45. Conclusion •The modern development experience is possible without full type annotations by TypeProf for IDE •Ruby 3.1 will bundle TypeProf for IDE 45