Rust Object Notation

RSON is a simple readable data serialization format that looks similar to Rust syntax. It's designed to support all of Serde's data model, so structs, enums, tuples, arrays, generic maps, and primitive values. RSON is a fork of RON library, but provides a more appropriate Rust-lang syntax.

Example in JSON

{
   "materials": {
        "metal": {
            "reflectivity": 1.0
        },
        "plastic": {
            "reflectivity": 0.5
        }
   },
   "entities": [
        {
            "name": "hero",
            "material": "metal"
        },
        {
            "name": "moster",
            "material": "plastic"
        }
   ]
}

Notice these issues:

1. Struct and maps are the same
   • random order of exported fields
     • annoying and inconvenient for reading
     • doesn't work well with version control
   • quoted field names
     • too verbose
   • no support for enums
2. No trailing comma allowed
3. No comments allowed

Same example in RSON

/*
 * Scene object example
 */
Scene { // class name is optional
    materials: { // this is a map
        "metal": {
            reflectivity: 1.0,
        },
        "plastic": {
            reflectivity: 0.5,
        },
    },
    entities: [ // this is an array
        { // this is an object
            name: "hero",
            material: "metal",
        },
        {
            name: "monster",
            material: "plastic",
        },
    ],
}

The RSON format uses {..} brackets for heterogeneous structures (classes) and homogeneous maps, where classes are different from maps by keys: in classes those are identifiers, but in maps those are values. Additionally, it uses (..) brackets for heterogeneous tuples, and [..] for homogeneous arrays. This distinction allows us to solve the biggest problem with JSON.

Same example in RON

Scene( // class name is optional
    materials: { // this is a map
        "metal": (
            reflectivity: 1.0,
        ),
        "plastic": (
            reflectivity: 0.5,
        ),
    },
    entities: [ // this is an array
        (
            name: "hero",
            material: "metal",
        ),
        (
            name: "monster",
            material: "plastic",
        ),
    ],
)

Unlike RSON, the RON format uses (..) brackets for all heterogeneous structures (classes and tuples), while preserving the {..} for maps, and [..] for homogeneous arrays. This is non-traditional syntax for classes of both the JSON and the native Rust representation.

RSON heterogeneous structures syntax

Here are the general rules to parse the heterogeneous structures:

Specification

There is a very basic, work in progress specification available on the wiki page.

Appendix

Why not XML?

• too verbose
• unclear how to treat attributes vs contents

Why not YAML?

• significant white-space
• specification is too big

Why not TOML?

• alien syntax
• absolute paths are not scalable

Why not RON?

• non-traditional syntax for classes
• confuse between class and map syntax
• does not support block comments

Why not XXX?

• if you know a better format, tell me!

License

RSON is dual-licensed under Apache-2.0 and MIT.