Release Note 3.5

Some of the highlights in RBS 3.5 are:

• Optional record keys (#1717, #1732)
• Untyped function parameters (#1806)
• Add lexer API (#1829, #1831)

You can install it with $ gem install rbs or using Bundler.

gem 'rbs', '~> 3.5.0.pre'

Read the CHANGELOG for the details.

Warning

• RBS 3.5 has many stdlib signature updates. Updating to 3.5 may cause having different type checking results.
• Using new syntax may cause issues with tools that doesn't support RBS 3.5

Optional record keys

Pull Requests: #1717, #1732

The record keys with ? prefix are optional.

type json = {
  ?id: Integer,
  name: String,
  email: String?
}

As you can see in types.rbs, the Types::Record type provides three methods.

class RBS::Types::Record
  attr_reader all_fields: Hash[Symbol, [t, bool]]
  attr_reader fields: Hash[Symbol, t]
  attr_reader optional_fields: Hash[Symbol, t]
end

The #fields only contains required fields, and optional_fields contains optional fields. It means the existing RBS based tools continue working but ignores optional fields.

Untyped function parameters

Pull Requests: #1806

Method type parameters and block parameters can be untyped with (?) syntax.

class Foo
  def dynamic: (?) -> void
end

class ActiveRecord::Base
  def self.scope: (Symbol) { (?) -> void } -> void
                | (Symbol, ^(?) -> void) -> void
end

Lexer API

Pull Requests: #1829, #1831

Parser.lex method returns the list of tokens from the input, without constructing syntax tree.

tokens = RBS::Parser.lex(source)

The tokens contains all tokens from the source code, including comments and trivia tokens.

You can use the API to implement linters or something that works on comments.