# MON Core (`mon-core`)
[](https://crates.io/crates/mon-core)
[](https://docs.rs/mon-core)
[](./LICENSE)
`mon-core` is the reference Rust implementation of the **MON (Mycel Object Notation)** language — a human-focused configuration and data format designed to be readable, safe, and predictable.
This crate provides the parser, analyzer, validator, and core data model used by MON-based tooling, servers, CLIs, and compilers.
> for more information please look at out website: www.mycel-lang.org
---
## Table of Contents
* [Overview](#overview)
* [Features](#features)
* [Example](#example)
* [Rust Quick Start](#rust-quick-start)
* [Error Handling](#error-handling)
* [Development](#development)
* [Roadmap](#roadmap)
* [License](#license)
---
## Overview
MON aims to replace overly rigid formats (JSON) and overly permissive ones (YAML) with a syntax that stays readable without giving up safety or predictability.
`mon-core` implements:
* A forgiving parser with clear, context-rich error messages
* A semantic analyzer with anchor/alias resolution
* Type checking via `#struct`, `#enum`, and validated bindings
* An internal IR suitable for compilers and higher-level tooling
If you want to embed MON into your Rust application or build tooling around the language, this is the crate.
For more information about mon [docs](docs/01_the_basic_structure.md) are here :D
---
## Features
* **Clean syntax:** unquoted keys, comments, trailing commas
* **Human-friendly booleans:** `on` / `off` as well as `true` / `false`
* **Anchors & aliases:** safe reuse with explicit copy semantics (`&name`, `*name`)
* **Deep merges:** `...*anchor` for structured overrides
* **Types built in:** `#struct`, `#enum`, and `::` for validation
* **Modular imports:** `import { A, B } from "./file.mon"`
* **Detailed errors:** location-aware, colorized, actionable
---
## Example
```mon
import { ServerSettings } from "./schemas.mon"
{
&base: {
host: "localhost",
port: 8080,
},
User: #struct {
id(Number),
name(String),
roles([String...]),
},
admin :: User = {
id: 1,
name: "Alice",
roles: ["admin", "editor"],
},
dev: {
...*base,
port: 9001,
debug: on,
},
}
```
---
## Rust Quick Start
Add to `Cargo.toml`:
```toml
[dependencies]
mon-core = "0.1"
```
Parse and analyze:
```rust
use mon_core::analyze;
fn main() {
let text = r#"
settings: {
name: "Example",
enabled: on,
}
"#;
match analyze(text, "config.mon") {
Ok(result) => {
println!("JSON:\n{}", result.to_json().unwrap());
}
Err(err) => {
eprintln!("MON error:\n{err}");
}
}
}
```
---
## Error Handling
MON is designed to fail loudly **and** helpfully.
Example error (format depends on your terminal capabilities):
```bash
error[E0012]: expected Number, got String
--> config.mon:7:12
|
```
Errors include:
* the source span
* the inferred and expected types
* suggestions when applicable
---
## Development
Build:
```bash
cargo build
```
Test:
```bash
cargo test --all-features
```
Checks:
```bash
cargo check
```
The project follows standard Rust layout.
Documentation lives in `docs/`. Any language or spec changes must be reflected there.
---
## Roadmap
* Improved parser recovery modes
* Type system stabilization
* Performance pass on alias/anchor resolution
* Better import graph validation
* Tooling support (formatter, LSP)
---
## License
Licensed under the MIT license.
See [`LICENSE`](./LICENSE) for details.
---
> for more information please look at out website: www.mycel-lang.org
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