Crate toon_macro 

toon-macro

Ergonomic macros for constructing and parsing TOON (Token-Oriented Object Notation) values.

TOON is a compact data format designed to convey the same information as JSON with 30-60% fewer tokens, making it ideal for LLM prompts and responses.

Features

• toon! macro: JSON-like Rust DSL for constructing TOON values
• toon_str! macro: Parse TOON-format strings at runtime
• ToonTable trait: Encode/decode tabular data efficiently
• #[derive(ToonTable)]: Automatic table serialization (requires derive feature)

Quick Start

Using toon! (Rust-DSL)

The toon! macro provides a JSON-like syntax for constructing TOON values:

use toon_macro::{toon, Value};

// Simple object
let user = toon!({
    name: "Alice",
    age: 30,
    active: true
});

// Nested structures
let data = toon!({
    config: {
        host: "localhost",
        port: 8080
    },
    users: [
        { id: 1, name: "Alice" },
        { id: 2, name: "Bob" }
    ]
});

// Using variables
let name = "Charlie";
let score = 95i64;
let result = toon!({
    name: name,
    score: score
});

Using toon_str! (TOON syntax)

The toon_str! macro parses TOON-format text at runtime:

use toon_macro::toon_str;

let config = toon_str!(r#"
host: "localhost"
port: 5432
active: true
"#);

Using from_toon_str (with error handling)

For fallible parsing, use from_toon_str directly:

use toon_macro::from_toon_str;

let input = r#"name: "Alice""#;
match from_toon_str(input) {
    Ok(value) => println!("Parsed: {:?}", value),
    Err(e) => eprintln!("Parse error: {}", e),
}

Using ToonTable (requires derive feature)

use toon_macro::ToonTable;

#[derive(ToonTable)]
struct User {
    id: u64,
    name: String,
    #[toon(rename = "user_role")]
    role: String,
}

let users = vec![
    User { id: 1, name: "Alice".into(), role: "admin".into() },
    User { id: 2, name: "Bob".into(), role: "user".into() },
];

// Encode to compact table format
let table = User::to_toon_table(&users);

// Decode back to structs
let decoded = User::from_toon_table(&table).unwrap();

Feature Flags

• serde (default): Enable serde integration for serializing arbitrary types
• derive: Enable #[derive(ToonTable)] macro
• pretty: Enable pretty-printing functions

Minimum Supported Rust Version

This crate requires Rust 1.70 or later.

Re-exports

pub use error::Error;

pub use error::Result;

pub use ser::from_toon_str;

pub use ser::to_toon_string;

pub use table::ToonTable;

pub use ser::deserialize;

pub use ser::serialize;

pub use value::from_value;

pub use value::to_value;

Modules

error

Unified error types for toon-macro.

internal

Internal helper macros and utilities.

macros

TOON construction macros.

ser

TOON serialization and deserialization utilities.

table

TOON table encoding and decoding.

value

TOON Value type and conversions.

Macros

toon

Construct a TOON Value using a JSON-like DSL.

toon_str

Parse a TOON-format string literal at runtime.

Enums

Number

Represents a TOON number.

Value

Represents any valid TOON value.

Type Aliases

Map

An order-preserving map type used for TOON objects.