rbs-files

Standalone RBS Files

Write type signatures in separate .rbs files in a sig/ directory. Ruby source files remain unchanged.

Quick Start

# sig/person.rbs
class Person
  attr_reader name: String
  attr_reader age: Integer?

  def initialize: (String name, ?Integer? age) -> void
  def greet: () -> String
end

File Structure

project/
├── lib/
│   └── person.rb          # Ruby implementation
├── sig/
│   ├── person.rbs         # Type signatures
│   ├── _private/          # Hidden from library users
│   │   └── internal.rbs
│   └── manifest.yaml      # Stdlib dependencies
└── Steepfile

Class and Module Declarations

# Basic class
class User
end

# With superclass
class Admin < User
end

# With type parameters
class Container[T]
end

# Module
module Logging
end

# Module with self-type constraint
module Enumerable[Elem] : _Each[Elem]
end

Method Definitions

class Calculator
  # Instance method
  def add: (Integer, Integer) -> Integer

  # Singleton (class) method
  def self.create: () -> Calculator

  # Module function (both singleton and private instance)
  def self?.sqrt: (Numeric) -> Float

  # Visibility
  private def internal: () -> void
end

Method Type Syntax

# Required positional
def foo: (String, Integer) -> void

# Optional positional (? prefix)
def foo: (String, ?Integer) -> void

# Rest positional
def foo: (*String) -> void

# Required keyword
def foo: (name: String) -> void

# Optional keyword
def foo: (?name: String) -> void

# Keyword rest
def foo: (**String) -> void

# Block (required)
def foo: () { (String) -> Integer } -> void

# Block (optional, ? before brace)
def foo: () ?{ (String) -> Integer } -> void

# Complex signature
def foo: (
  String,                    # Required positional
  ?Integer,                  # Optional positional
  *Symbol,                   # Rest positional
  name: String,              # Required keyword
  ?age: Integer,             # Optional keyword
  **untyped                  # Keyword rest
) { (String) -> void } -> Array[String]