Toon Language Support

A Visual Studio Code extension providing comprehensive language support for Toon files, including syntax highlighting, hover information, jump-to-definition, and real-time error detection.

Overview

Toon stands for Token-Oriented Object Notation - a structured data format language optimized for AI systems. Toon provides a clean, readable syntax for representing configuration data, metadata, and structured information in a way that's both human-friendly and ideal for AI-driven workflows.

Toon is designed to be simple yet powerful, supporting three main syntax patterns: key-value pairs for configuration, simple arrays with size validation, and structured arrays for tabular data with typed columns.

Features

Language Syntax

Toon supports three primary syntax patterns for organizing data:

Key-Value Pairs

Simple key-value pairs for configuration and metadata. Perfect for storing context, settings, and properties.

context:
  task: Our favorite hikes together
  location: Boulder
  season: spring_2025

Use case: Configuration files, metadata, simple data structures

Simple Arrays

Arrays with explicit size declarations and comma-separated values. The extension validates that the number of values matches the declared size.

friends[3]: ana,luis,sam

Use case: Lists of items where size validation is important

Structured Arrays

Tabular data with field definitions and multi-line data rows. Each row must have values matching the declared fields.

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

Use case: Structured data, tables, records with multiple fields

Extension Capabilities

Syntax Highlighting

The extension automatically recognizes .toon files and provides color coding for:

• Keys and field names
• Values and data
• Array declarations and sizes
• Structural elements (brackets, braces, colons)

Hover Information

Hover over elements in your Toon files to see contextual information:

• Structured array values: Displays the field name for each value
• Array elements: Shows index information
• Keys: Displays key information for key-value pairs

Simply hover your mouse over any element to see its details.

Jump to Definition

Navigate quickly from structured array data values to their field definitions:

• F12: Jump to definition
• Ctrl+Click (Cmd+Click on macOS): Jump to definition

This feature works with structured arrays, allowing you to jump from a data value back to the field declaration.

Error Detection

The extension provides real-time validation with four specialized validators:

ArraySizeValidator

• Detects when the number of array values doesn't match the declared size
• Reports both insufficient and exceeded array sizes
• Works for both simple arrays and structured array row counts

StructuredArrayFieldValidator

• Validates that each data row has the correct number of fields
• Detects missing fields (insufficient count)
• Detects extra fields (exceeded count)
• Each inconsistent row gets its own diagnostic

KeyValuePairValidator

• Ensures key-value pairs have proper syntax
• Detects missing colons
• Detects empty keys or values
• Validates key-value pair structure

ArraySyntaxValidator

• Validates array declaration syntax
• Checks for missing closing brackets
• Ensures array size is specified
• Validates that size is numeric
• Checks structured array brace syntax

All errors are displayed inline with red squiggly underlines and appear in the Problems panel.

Getting Started

Installation

1. Open Visual Studio Code
2. Go to the Extensions view (Ctrl+Shift+X or Cmd+Shift+X on macOS)
3. Search for "Toon Language Support"
4. Click Install

Usage

1. Create a new file with the .toon extension
2. Start writing Toon syntax - syntax highlighting will activate automatically
3. Use hover, jump-to-definition, and error detection features as you work
4. Check the Problems panel for any validation errors

Examples

Here's a complete example demonstrating all Toon features:

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

More examples can be found in the example/ directory of this repository:

• simple.toon - Key-value pairs
• array.toon - Simple arrays
• array_with_keys.toon - Structured arrays