Decodal/README.md

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# Decodal
Decodal is a small deterministic DSL for describing, composing, validating, and materializing structured data.
It is designed around a lightweight Rust library:
- host-supplied imports through `SourceLoader`
- no filesystem access in the library core
- concrete and abstract values with constraints and defaults
- deterministic expression evaluation
- optional regex support behind a Cargo feature
- browser playground support through WebAssembly
## Library crate
Embedded hosts should depend on `decodal` and provide imports with a `SourceLoader`.
```toml
[dependencies]
decodal = "0.1"
```
## Derive support
For embedded Rust applications, Decodal can generate a schema and typed decoder from a Rust struct with the `derive` feature.
```toml
[dependencies]
decodal = { version = "0.1", features = ["derive"] }
```
```rust
use decodal::{Decodal, DecodalDecode, DecodalSchema, Engine};
#[derive(Decodal)]
struct Service {
name: String,
#[decodal(gt = 443, default = 8443)]
port: i64,
#[decodal(rename = "feature.enable", default = true)]
feature_enabled: bool,
}
```
The derive implements:
- `DecodalSchema`, which produces a host schema for `Engine::bind_global`
- `DecodalDecode`, which converts materialized `Data` into the Rust struct
## CLI
A standalone CLI is kept in this repository as the `decodal-cli` workspace package.
It builds a `decodal` binary, but it is not the primary crates.io package.
Run a Decodal file from the repository:
```sh
cargo run -q -p decodal-cli -- examples/advanced/main.dcdl
```
Enable optional regex support when needed:
```sh
cargo run -q -p decodal-cli --features regex -- examples/regex/main.dcdl
```
## Web playground
The static documentation site and browser playground live under:
```text
site/decodal-site/
```
## License
Licensed under either of:
- Apache License, Version 2.0
- MIT license
at your option.