RBS Stdlib

Generate and manage RBS type signatures for gems and Ruby standard library usage.

Instructions

1. RBS Collections

RBS uses collections to manage gem type signatures:

# rbs_collection.yaml
sources:
  - type: git
    name: ruby/gem_rbs_collection
    remote: https://github.com/ruby/gem_rbs_collection.git
    revision: main
    repo_dir: gems

path: .gem_rbs_collection

gems:
  - name: rails
  - name: activerecord
  - name: activesupport
  - name: sidekiq

2. Initialize RBS Collection

# Create rbs_collection.yaml
rbs collection init

# Install gem signatures
rbs collection install

# Update signatures
rbs collection update

3. Stdlib Types

Ruby stdlib types are included with RBS:

# List available stdlib signatures
rbs list

# Use stdlib in validation
rbs -r set -r json validate

# Check stdlib signature
rbs -r net-http methods Net::HTTP

4. Common Stdlib Requires

gems:
  # Core extensions
  - name: set
  - name: json
  - name: yaml
  - name: erb

  # Networking
  - name: net-http
  - name: uri
  - name: socket

  # File operations
  - name: fileutils
  - name: pathname
  - name: tempfile

  # Data formats
  - name: csv
  - name: rexml

  # Utilities
  - name: logger
  - name: optparse
  - name: benchmark

5. Generate RBS for Custom Gems

When gem has no published types:

# Generate prototype from gem source
rbs prototype rb /path/to/gem/lib/**/*.rb > sig/gems/my_gem.rbs

# Generate from runtime
typeprof /path/to/gem/lib/my_gem.rb -o sig/gems/my_gem.rbs

6. Steepfile Configuration

# Steepfile
target :app do
  signature "sig"

  # Load gem signatures
  library "set"
  library "json"
  library "pathname"

  # Load from collection
  collection_config "rbs_collection.yaml"

  check "lib"
  check "app"
end

7. Common Gem Type Patterns

Rails ActiveRecord:

class User < ApplicationRecord
  def posts: () -> Post::ActiveRecord_Associations_CollectionProxy
  def organization: () -> Organization?
end

Sidekiq Workers:

class MyWorker
  include Sidekiq::Worker
  def perform: (Integer user_id, String action) -> void
end

Faraday HTTP:

class ApiClient
  @connection: Faraday::Connection
  def get: (String path) -> Faraday::Response
end

8. Handling Missing Types

When types aren't available:

1. Check gem_rbs_collection on GitHub

2. Create stub types:

# sig/gems/missing_gem.rbs
module MissingGem
  def self.configure: () { (untyped) -> void } -> void

  class Client
    def initialize: (?String api_key) -> void
    def request: (String endpoint) -> untyped
  end
end

3. Use untyped strategically:

class MyService
  @external_client: untyped  # Third-party without types
  def process: () -> String  # Still type your code
end

9. Updating Gem Types

# Update all collections
rbs collection update

# Reinstall after Gemfile changes
bundle install && rbs collection install

Setup Workflow

1. Initialize project:

rbs collection init

2. Edit rbs_collection.yaml:

sources:
  - type: git
    name: ruby/gem_rbs_collection
    remote: https://github.com/ruby/gem_rbs_collection.git
    revision: main
    repo_dir: gems

path: .gem_rbs_collection

gems:
  - name: activesupport
    version: "7.0"

3. Install signatures:

rbs collection install

4. Create Steepfile:

target :app do
  signature "sig"
  collection_config "rbs_collection.yaml"
  check "lib", "app"
end

5. Validate setup:

steep check