Skip to content
/ sord Public

Convert YARD docs to Sorbet RBI and Ruby 3/Steep RBS files


Notifications You must be signed in to change notification settings


Repository files navigation



Sord is a Sorbet and YARD crossover. It can automatically generate RBI and RBS type signature files by looking at the types specified in YARD documentation comments.

If your project is already YARD documented, then this can generate most of the type signatures you need!

Sord is the perfect way to jump-start the adoption of types in your project, whether you plan to use Sorbet's RBI format or Ruby 3/Steep's RBS format.

Try Sord online at:

Sord has the following features:

  • Automatically generates signatures for modules, classes and methods
  • Support for multiple parameter or return types (T.any/|)
  • Gracefully handles missing YARD types (T.untyped/untyped)
  • Can infer setter parameter type from the corresponding getter's return type
  • Recognises mixins (include and extend)
  • Support for generic types such as Array<T> and Hash<K, V>
  • Can infer namespaced classes ([Bar] can become GemName::Foo::Bar)
  • Handles return types which can be nil (T.nilable/untyped)
  • Handles duck types (T.untyped/untyped)
  • Support for ordered list types ([Array(Integer, Symbol)] becomes [Integer, Symbol])
  • Support for boolean types ([true, false] becomes T::Boolean/bool)
  • Support for &block parameters documented with @yieldparam and @yieldreturn


Install Sord with gem install sord.

Sord is a command line tool. To use it, open a terminal in the root directory of your project and invoke sord, passing a path where you'd like to save your file (this file will be overwritten):

sord defs.rbi

Sord will generate YARD docs and then print information about what it's inferred as it runs. It is best to fix any issues in the YARD documentation, as any edits made to the resulting file will be replaced if you re-run Sord.

The output type is inferred by the file extension you use, but you can also specify it explicitly with --rbi or --rbs.

Shipping RBI Types

RBI files generated by Sord can be used in two main ways:

Generally, you should ship the type signatures with your gem if possible. sorbet-typed is meant to be a place for gems that are no longer updated or where the maintainer is unwilling to ship type signatures with the gem itself.


Sord also takes some flags to alter the generated file:

  • --rbi/--rbs: Override the output format inferred from the file extension.
  • --no-sord-comments: Generates the file without any Sord comments about warnings/inferences/errors. (The original file's comments will still be included.)
  • --no-regenerate: By default, Sord will regenerate a repository's YARD docs for you. This option skips regenerating the YARD docs.
  • --break-params: Determines how many parameters are necessary before the signature is changed from a single-line to a multi-line block. (Default: 4)
  • --replace-errors-with-untyped: Uses T.untyped instead of SORD_ERROR_* constants.
  • --replace-unresolved-with-untyped: Uses T.untyped when Sord is unable to resolve a constant.
  • --include-messages and --exclude-messages: Used to filter the logging messages given by Sord. --include-messages acts as a whitelist, printing only messages of the specified logging kinds, whereas --exclude-messages acts as a blacklist and suppresses the specified logging kinds. Both flags take a comma-separated list of logging kinds, for example omit,infer. When using --include-messages, the done kind is included by default. (You cannot specify both --include-messages and --exclude-messages.)
  • --exclude-untyped: Exclude methods and attributes with untyped return values.
  • --tags TAGS: Provide a list of comma-separated tags as understood by the yard command. E.g. `--tags 'mytag:My Description,mytag2:My New Description'


Say we have this file, called test.rb:

module Example
  class Person
    # @param name [String] The name of the Person to create.
    # @param age [Integer] The age of the Person to create.
    # @return [Example::Person]
    def initialize(name, age)
      @name = name
      @age = age

    # @return [String]
    attr_accessor :name

    # @return [Integer]
    attr_accessor :age

    # @param possible_names [Array<String>] An array of potential names to choose from.
    # @param possible_ages [Array<Integer>] An array of potential ages to choose from.
    # @return [Example::Person]
    def self.construct_randomly(possible_names, possible_ages), possible_ages.sample)

First, generate a YARD registry by running yardoc test.rb. Then, we can run sord test.rbi to generate the RBI file. (Careful not to overwrite your code files! Note the .rbi file extension.) In doing this, Sord prints:

[INFER] Assuming from filename you wish to generate in RBI format
[DONE ] Processed 8 objects (2 namespaces and 6 methods)

The test.rbi file then contains a complete RBI file for test.rb:

# typed: strong
module Example
  class Person
    # _@param_ `name` — The name of the Person to create.
    # _@param_ `age` — The age of the Person to create.
    sig { params(name: String, age: Integer).void }
    def initialize(name, age); end

    # _@param_ `possible_names` — An array of potential names to choose from.
    # _@param_ `possible_ages` — An array of potential ages to choose from.
    sig { params(possible_names: T::Array[String], possible_ages: T::Array[Integer]).returns(Example::Person) }
    def self.construct_randomly(possible_names, possible_ages); end

    sig { returns(String) }
    attr_accessor :name

    sig { returns(Integer) }
    attr_accessor :age

If we had instead generated test.rbs, we would get this file in RBS format:

module Example
  class Person
    # _@param_ `name` — The name of the Person to create.
    # _@param_ `age` — The age of the Person to create.
    def initialize: (String name, Integer age) -> void

    # _@param_ `possible_names` — An array of potential names to choose from.
    # _@param_ `possible_ages` — An array of potential ages to choose from.
    def self.construct_randomly: (Array[String] possible_names, Array[Integer] possible_ages) -> Example::Person

    attr_accessor name: String

    attr_accessor age: Integer

Things to be aware of

The general rule of thumb for type conversions is:

  • If Sord understands the YARD type, then it is converted into the RBI or RBS type.
  • If the YARD type is missing, Sord fills in T.untyped.
  • If the YARD type can't be understood, Sord creates an undefined Ruby constant with a similar name to the unknown YARD type. For example, the obviously invalid YARD type A%B will become a constant called SORD_ERROR_AB. You should search through your resulting file to find and fix and SORD_ERRORs.


Bug reports and pull requests are welcome on GitHub at This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

While contributing, if you want to see the results of your changes to Sord you can use the examples:seed Rake task. The task uses Sord to generate types for a number of open source Ruby gems, including Bundler, Haml, Rouge, and RSpec. rake examples:seed (and rake examples:reseed to regenerate the files) will clone the repositories of these gems into sord_examples/ and then generate the files into the same directory.


The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the Sord project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.