JSON to TOON Package

A Flutter/Dart package for converting between JSON and TOON (Token-Oriented Object Notation) formats.

What is TOON?

TOON (Token-Oriented Object Notation) is a compact, human-readable encoding of the JSON data model specifically designed for LLM prompts. It provides:

• 30-60% fewer tokens compared to JSON
• Lossless conversion - maintains all data integrity
• Human-readable format using YAML-like indentation
• Tabular arrays for uniform object arrays (CSV-style)
• Minimal punctuation to reduce token count

Features

✅ Convert JSON to TOON format
✅ Convert TOON to JSON format
✅ Support for all JSON data types (objects, arrays, primitives)
✅ Tabular format for uniform arrays
✅ Proper string escaping and quoting
✅ Comprehensive test coverage

Installation

Add this to your package's pubspec.yaml file:

dependencies:
  json_to_toon: ^1.0.0

Or install from local path:

dependencies:
  json_to_toon:
    path: ../json_to_toon_package

Then run:

flutter pub get

Usage

Basic Usage

import 'package:json_to_toon/json_to_toon.dart';

void main() {
  final converter = ToonConverter();
  
  // JSON to TOON
  final jsonData = {
    'name': 'Alice',
    'age': 30,
    'active': true
  };
  
  final toon = converter.toToon(jsonData);
  print(toon);
  // Output:
  // name: Alice
  // age: 30
  // active: true
  
  // TOON to JSON
  final decoded = converter.fromToon(toon);
  print(decoded); // {name: Alice, age: 30, active: true}
}

Converting from JSON String

final converter = ToonConverter();

// JSON string to TOON
final jsonString = '{"name":"Bob","age":25}';
final toon = converter.jsonToToon(jsonString);

// TOON to JSON string
final json = converter.toonToJson(toon);

Working with Arrays

final data = {
  'colors': ['red', 'green', 'blue'],
  'users': [
    {'id': 1, 'name': 'Alice'},
    {'id': 2, 'name': 'Bob'}
  ]
};

final toon = converter.toToon(data);
print(toon);
// Output:
// colors[3]: red,green,blue
// users[2]{id,name}:
//   1,Alice
//   2,Bob

Using Individual Encoder/Decoder

import 'package:json_to_toon/json_to_toon.dart';

// Using encoder only
final encoder = ToonEncoder();
final toon = encoder.encode({'key': 'value'});

// Using decoder only
final decoder = ToonDecoder();
final data = decoder.decode('key: value');

TOON Format Examples

Simple Object

JSON:

{
  "name": "Alice",
  "age": 30,
  "active": true
}

TOON:

name: Alice
age: 30
active: true

Nested Object

JSON:

{
  "user": {
    "name": "Bob",
    "email": "bob@example.com"
  }
}

TOON:

user:
  name: Bob
  email: bob@example.com

Array of Objects (Tabular)

JSON:

{
  "hikes": [
    {"id": 1, "name": "Blue Lake Trail", "distance": 7.5},
    {"id": 2, "name": "Ridge Overlook", "distance": 9.2}
  ]
}

TOON:

hikes[2]{id,name,distance}:
  1,Blue Lake Trail,7.5
  2,Ridge Overlook,9.2

Complex Example

JSON:

{
  "context": {
    "task": "Our favorite hikes",
    "location": "Boulder"
  },
  "friends": ["ana", "luis", "sam"],
  "hikes": [
    {"id": 1, "name": "Blue Lake Trail", "distanceKm": 7.5},
    {"id": 2, "name": "Ridge Overlook", "distanceKm": 9.2}
  ]
}

TOON:

context:
  task: Our favorite hikes
  location: Boulder
friends[3]: ana,luis,sam
hikes[2]{id,name,distanceKm}:
  1,Blue Lake Trail,7.5
  2,Ridge Overlook,9.2

API Reference

ToonConverter

Main class that combines encoding and decoding functionality.

Methods:

• String toToon(dynamic data) - Convert Dart object to TOON
• String jsonToToon(String jsonString) - Convert JSON string to TOON
• dynamic fromToon(String toonString) - Convert TOON to Dart object
• String toonToJson(String toonString) - Convert TOON to JSON string

ToonEncoder

Encodes JSON/Dart objects to TOON format.

Constructor:

• ToonEncoder({String indent = ' '}) - Create encoder with custom indentation

Methods:

• String encode(dynamic json) - Encode data to TOON
• String encodeFromJson(String jsonString) - Encode JSON string to TOON

ToonDecoder

Decodes TOON format to JSON/Dart objects.

Methods:

• dynamic decode(String toon) - Decode TOON to Dart object
• String decodeToJson(String toon) - Decode TOON to JSON string

Running Tests

cd json_to_toon_package
flutter test

Running the Example App

cd json_to_toon_package/example
flutter run

The example app provides an interactive UI to convert between JSON and TOON formats.

Benefits of TOON

1. Token Efficiency: Reduces token count by 30-60% compared to JSON
2. Cost Savings: Lower API costs when working with LLMs
3. Better Context: More data fits in LLM context windows
4. Human Readable: Easy to read and understand
5. Lossless: Perfect round-trip conversion with JSON

Use Cases

• Optimizing prompts for Large Language Models (LLMs)
• Reducing API costs for AI services
• Efficient data serialization for token-limited contexts
• Human-readable configuration files
• Data interchange in AI applications

Specification

This package implements the official TOON specification v2.0. For more details, see:

• TOON Specification
• TOON Format Repository

License

MIT License

Contributing

Contributions are welcome! Please feel free to submit issues or pull requests.

Author

Created for efficient JSON-TOON conversion in Flutter/Dart applications.