RbToon

Toon is a structural text format optimized for LLM input. RbToon is a Racc-based decoder gem that decodes Toon input into Ruby objects.

Installation

Install the gem and add to the application's Gemfile by executing:

bundle add rbtoon

If bundler is not being used to manage dependencies, install the gem by executing:

gem install rbtoon

Usage

You can use the methods below to decode Toon into Ruby objects.

• Decode the given Toon string
  • RbToon.decode
• Decode the Toon string read from the given file path
  • RbToon.decode_file

All hash keys are symbolized when the symbolize_names option is set to true.

require 'rbtoon'

toon = RbToon.decode(<<~'TOON', symbolize_names: true)
  context:
    task: Our favorite hikes together
    location: Boulder
    season: spring_2025
  friends[3]: ana,luis,sam
  hikes[3]{id,name,distanceKm,elevationGain,companion,wasSunny}:
    1,Blue Lake Trail,7.5,320,ana,true
    2,Ridge Overlook,9.2,540,luis,false
    3,Wildflower Loop,5.1,180,sam,true
TOON

# output
# {context: {task: "Our favorite hikes together", location: "Boulder", season: "spring_2025"},
#  friends: ["ana", "luis", "sam"],
#  hikes:
#   [{id: 1, name: "Blue Lake Trail", distanceKm: 7.5, elevationGain: 320, companion: "ana", wasSunny: true},
#    {id: 2, name: "Ridge Overlook", distanceKm: 9.2, elevationGain: 540, companion: "luis", wasSunny: false},
#    {id: 3, name: "Wildflower Loop", distanceKm: 5.1, elevationGain: 180, companion: "sam", wasSunny: true}]}

The RbToon::ParseError exception is raised if the given Toon includes errors listed in here.

begin
  RbToon.decode(<<~'TOON')
    freends[4]: ana,Luis,sam
  TOON
rescue RbToon::ParseError => e
  puts e
end

# output
# expected 4 array items, but got 3 -- filename: unknown line: 1 column: 8

For more details about APIs, please visit the documentation page.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/taichi-ishitani/rbtoon.

• Issue Tracker
• Pull Request
• Discussion

License

Copyright © 2025 Taichi Ishitani. RbToon is licensed under the terms of the MIT License, see LICENSE.txt for further details.