The newsletter of RBS updates

At RubyKaigi Takeout 2021
https://rubykaigi.org/2021-takeout/presentations/p_ck_.html

ref: https://github.com/pocke/rubykaigi-2021

If you want to click in the slides, I recommend seeing https://docs.google.com/presentation/d/e/2PACX-1vREU6ZguqLxGk_k1l3zvKbRo_TbMTKN3yEgfzrjA85foVXrmeYvWnOTefsaBycsb9m6H924VsZw_YKt/pub?start=false&loop=false&delayms=3000 instead.

Transcript

1. The newsletter of RBS
   updates
   RubyKaigi Takeout 2021🍔💨
   Sep. 10th
   

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2. pp self
   ● Masataka Pocke Kuwabara
   ● Software Engineer at Bit Journey, Inc.
   ○ Developing Kibela, an information sharing tool. https://kibe.la
   ● A maintainer of RBS
   ● A CRuby committer since Mar. 2021 ← NEW!
   

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3. First, Thanks for all RBS contributors!👏👏
   AaronC81, Adrian-Hirt, Afront, CariWest, HoneyryderChuck, MITSUBOSHI, Morriar,
   PanosCodes, YutaGoto, Yuuki77, a2ikm, ahazem, aikyo02, alts, andrewmcodes,
   berkos, cky, connorshea, donaldong, duderman, floor114, guillaumebriday, hanachin,
   hargoniX, hjwylde, hsbt, jeremyevans, jocmp, johansenja, k0kubun, kachick,
   kddnewton, kmizu, ko1, ksss, kunitoo, kyanny, linhpham, mame, marcandre,
   masahito1997, meganemura, mihyaeru21, mtsmfm, natsuokawai, nobu,
   ochaochaocha3, ohbarye, palkan, pocke, pointlessone, raosush, s4na, satoryu,
   sbeckeriv, soutaro, south37, szTheory, tadd, taki, waka, wat-aro, ybiquitous,
   ykpythemind, ysakasin
   note: ascii order, (..Time.parse('2020-08-20').cover?(contributed_at)
   full list: https://github.com/ruby/rbs/graphs/contributors and
   https://github.com/ruby/gem_rbs_collection/graphs/contributors
   

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4. Goal
   ● You get hints to introduce RBS to your application
   ● Announce RBS updates for Ruby 3.1
   ○ RBS v2 will be released for Ruby 3.1
   

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5. Support page
   This talk is pre-recording, so it may have updates between
   recording and event date. I wrote the additional information into
   the following GitHub repository.
   https://github.com/pocke/rubykaigi-2021
   And I’m watching this talk so feel free to ask me!
   

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6. Agenda: RBS Updates
   ● Introduce RBS and related softwares
   ● New feature: rbs collection
   ○ The main topic!
   ● Language Updates (Thanks soutaro-san!)
   ○ Bounded type parameter
   ○ Generic type aliases
   ● Other updates
   ○ Signature updates
   ○ Performance Improvements
   

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7. Introduce RBS and related
   softwares
   

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8. What’s is RBS?
   ● RBS is a language to describe Ruby types.
   ● It is a bundled gem since Ruby 3.0.
   ● You can also gem install rbs in Ruby 2.6+
   

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9. Repositories
   RBS is developed under two GitHub repositories
   ● https://github.com/ruby/rbs
   ○ the rbs gem
   ○ rbs command, rbs library, and RBS files for Ruby builtin and stdlibs.
   ● https://github.com/ruby/gem_rbs_collection
   ○ RBS for 3rd party gems, such as rails, nokogiri, etc
   ○ Similar to DefinitelyTyped in TypeScript
   

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10. Let’s contriubte to ruby/gem_rbs_collection
    ● It’s one of the easiest parts to contribute RBS
    ● We recommend writing gem RBS partially
    ○ RBS for gem’s all features is not required, focus the main features
    

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11. Related softwares
    ● TypeProf: https://github.com/ruby/typeprof
    ○ A type analysis tool for Ruby code based on abstract interpretation
    ● Steep: https://github.com/soutaro/steep
    ○ Static Type Checker, using RBS
    ● RBS Rails: https://github.com/pocke/rbs_rails
    ○ RBS generator for Ruby on Rails
    ● Sorbet: https://github.com/sorbet/sorbet
    ○ Static Type Checker, using RBI (another language describes Ruby Type)
    

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12. New feature: rbs collection
    

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13. New feature: rbs colllection
    ● It manages dependent libraries’ RBSs
    ○ In short, Bundler for RBS
    ● I’m developing this feature
    ● rbs collection command has been released!
    ○ As experimental for now, it will be GA on RBS v2
    ○ You can use it with gem install rbs now💎
    

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14. Motivation
    Before rbs collection, managing libraries’ RBSs is not
    smart.
    Let’s look an example to prepare libraries’ RBSs for a Rails
    app
    

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15. Motivating Example: Enable RBSs for a Rails app
    First, download gem_rbs_collection as git submodule
    $ git submodule add
    https://github.com/ruby/gem_rbs_collection.g
    it gem_rbs_collection
    

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16. Motivating Example: Enable RBSs for a Rails app
    Then, rbs command is available with the following super many
    options!
    $ rbs -rlogger -rpathname -rmutex_m -rdate
    -rmonitor -rsingleton -rtsort -rtime
    --repo=gem_rbs_collection -rrack -ractivesupport
    -ractionpack -ractivejob -ractivemodel
    -ractionview -ractiverecord -rrailties validate
    

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17. Motivating Example: Enable RBSs for a Rails app
    TypeProf needs the same options
    $ typeprof -rlogger -rpathname -rmutex_m -rdate
    -rmonitor -rsingleton -rtsort -rtime
    --repo=gem_rbs_collection -rrack -ractivesupport
    -ractionpack -ractivejob -ractivemodel
    -ractionview -ractiverecord -rrailties target.rb
    

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18. Example: Enable RBSs for a Rails app (step 4)
    And, Steep needs another configuration file, Steepfile.
    target :app do
    signature 'sig'
    check 'app'
    repo_path "gem_rbs_collection"
    library 'pathname', 'logger', 'mutex_m', 'date', 'monitor',
    'singleton', 'tsort', 'time', 'rack', 'activesupport', 'actionpack',
    'activejob', 'activemodel', 'actionview', 'activerecord', 'railties'
    end
    

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19. Conclusion of the motivations
    ● We need resolve dependencies by hand
    ○ The above examples, the human resolves “my app depends on Active
    Support, then Active Support depends on logger and …”
    ● To download, We need git submodule or copying RBSs
    ○ It’s too primitive. How controlling versions of 3rd party RBSs?
    ● To load, We need different ways between RBS, Steep,
    and TypeProf
    

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20. rbs collection solves the
    problems!
    

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21. What’s rbs collection?
    ● rbs collection is a command to manage libraries’ RBSs
    ● It does the following things
    ○ Resolve dependencies automatically
    ○ Download necessary RBSs
    ○ Load RBSs from one configuration file
    

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22. Usage example: rbs collection for a Rails app
    First, you need to generate the configuration file,
    rbs_collection.yaml
    # to install the latest version of RBS
    $ gem install rbs
    $ rbs collection init
    created: rbs_collection.yaml
    

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23. Usage example: rbs collection for a Rails app
    Then, edit the generated config file, add the following line
    + gems: [name: pathname, name: logger, name:
    mutex_m, name: date, name: monitor, name:
    singleton, name: tsort, name: time, name:
    set]
    (I’ll describe meaning of this diff)
    

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24. Usage example: rbs collection for a Rails app
    Then install RBSs.
    Note that rbs collection needs Gemfile.lock to resolve
    the dependencies
    $ vim Gemfile && bundle install
    $ rbs collection install
    

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25. Usage example: rbs collection for a Rails app
    Finally you can use RBS related tools without CLI options!
    $ rbs validate
    $ typeprof target.rb
    $ steep init && steep check
    Everything is going well! (NOTE: Steep and TypeProf haven’t
    been implemented yet maybe)
    

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26. Mechanism of rbs collection
    

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27. Mechanism of rbs collection
    ● It resolves dependencies with Gemfile.lock, and writes
    them to the lockfile, rbs_collection.lock.yaml
    ● It copies libraries’ RBSs with the lockfile from the sources,
    ruby/gem_rbs_collection GitHub repo in most cases.
    ● It loads RBSs with the lockfile for rbs, typeprof, steep
    commands.
    

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28. Known Issue
    ● rbs collection doesn’t resolve dependencies of standard
    libraries
    ○ For example, logger, optparse, etc…
    ○ Because standard libraries don’t need to be added to gemspec/Gemfile in
    order to require.
    ● I’ll fix this problem soon by introducing a configuration file,
    such as manifest.yaml to each gem
    

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29. New feature: Bounded Type
    Parameters
    

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30. Bounded Type Parameters
    RBS v2 will introduce Bounded Type Parameters.
    It allows you to specify an upper bound to Type Parameters.
    

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31. Motivating Example: PrettyPrint class
    ● The first parameter of PrettyPrint.new is the
    destination of printing.
    ○ e.g. PrettyPrint.new(str)
    ○ The output is given with << method
    

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32. Motivating Example: PrettyPrint classs
    PrettyPrint.new("") # OK (String#<<)
    PrettyPrint.new(STDOUT) # OK (IO#<<)
    PrettyPrint.new([]) # OK (Array#<<)
    PrettyPrint.new(true) # Error (No TrueClass#<<)
    PrettyPrint.new(3) # Error (Integer#<< doesn't
    accept String)
    

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33. Without bounded type parameters
    # RBS
    class PrettyPrint
    attr_reader output: _PPOut
    def initialize:
    (?_PPOut output) -> void
    end
    interface _PPOut
    def <<: (String) -> void
    end
    # Ruby
    PrettyPrint.new("")
    .output.size
    # _PPOut doesn't have #size
    PrettyPrint.new([])
    .output.join("")
    # _PPOut doesn't have #join
    

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34. Bounded type parameters solve this problem
    # RBS
    class PrettyPrint[X < _PPOut]
    attr_reader output: X
    def initialize:
    (?X output) -> void
    end
    interface _PPOut
    def <<: (String) -> void
    end
    # Ruby
    PrettyPrint.new("")
    .output.size
    # X == String, String#size
    exists
    PrettyPrint.new([])
    .output.join("")
    # X == Array, Array#join exists
    

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35. New feature: Generic Type Aliases
    

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36. Generic Type Aliases
    RBS v2 will introduce generic type aliases.
    

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37. Motivating Example: defining tree types
    type int_tree = {
    value: Integer,
    left: int_tree?,
    right: int_tree?
    }
    type string_tree = {
    value: String,
    left: string_tree?,
    right: string_tree?
    }
    We need to define the most same types for each type.
    

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38. Generic Type Aliases solve this problem
    type tree[T] = {
    value: T,
    left: tree[T]?,
    right: tree[T]?
    }
    type int_tree =
    tree[Integer]
    type string_tree =
    tree[String]
    type cat_tree =
    tree[Cat]
    We can define generic tree[T] type to make them DRY!
    

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39. Other updates
    

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40. Other updates
    ● Signature updates
    ○ 80 RBS files added/updated since RBS v1 for Ruby 3.0
    ● Performance Improvements
    ○ rbs validate command has been 3x faster than RBS v1
    ○ Parsing RBS will be 5x faster by an RBS parser written in C by soutaro-san
    ● Many bug fixes
    See the CHANGELOG for full changes!
    https://github.com/ruby/rbs/blob/master/CHANGELOG.md
    

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41. Conclusion
    

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42. Conclusion
    ● RBS v2 will introduces many new features, such as rbs
    collection and language updates
    ● It also includes signature updates, performance
    improvements
    ● We’re developing RBS for Ruby v3.1!
    Thanks for listening!
    

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