# rhai_rustler
[](https://github.com/fabriziosestito/rhai_rustler/actions/workflows/main.yaml)
[](https://github.com/fabriziosestito/rhai_rustler/actions/workflows/rust-ci.yaml)
[](https://github.com/fabriziosestito/rhai_rustler/actions/workflows/release.yaml)
[](https://hex.pm/packages/rhai_rustler)
[](https://hexdocs.pm/rhai_rustler/)
Elixir NIF bindings for Rhai, a tiny, simple and fast embedded scripting language for Rust that gives you a safe and easy way to add scripting to your applications.
Please refer to [The Rhai Book](https://rhai.rs/book/index.html) for extended information about the language.
## Installation
Add `:rhai_rustler` to the list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:rhai_rustler, "~> 1.0.0"}
]
end
```
## Features
`rhai_rustler` exposes a subset of the Rhai API to Elixir:
- [Engine]() - [Rhai Book](https://rhai.rs/book/engine/index.html) - [docs.rs](https://docs.rs/rhai/latest/rhai/struct.Engine.html)
- [Scope]() - [Rhai book](https://rhai.rs/book/engine/scope.html) - [docs.rs](https://docs.rs/rhai/latest/rhai/struct.Scope.html)
- [AST]() - [Rhai book](https://rhai.rs/book/engine/ast.html) - [docs.rs](https://docs.rs/rhai/latest/rhai/struct.Ast.html)
Note that not all the Rhai API features are supported. For instance, advanced and low-level APIs are not exposed.
If any usage patterns become apparent, they will be included in the future.
Please refer to [NIF bindings](guides/nif-bindings.md) to see the methods supported by the Elixir NIF.
The Elixir NIF provides a way to extend Rhai with external native Rust modules, see: [Extending Rhai with external native Rust modules](#extending-rhai-with-external-native-rust-modules) and [rhai_dylib](https://github.com/rhaiscript/rhai-dylib) for more information.
To check the supported types conversion, see [Type conversion table](#type-conversion-table).
## Usage patterns
### "Hello Rhai"
```elixir
engine = Rhai.Engine.new()
{:ok, "Hello Rhai!"} = Rhai.Engine.eval(engine, "\"Hello Rhai!\"")
```
### Eval
```elixir
engine = Rhai.Engine.new()
# Simple evaluation
{:ok, 2} = Rhai.Engine.eval(engine, "1 + 1")
# Evaluation with scope
scope = Rhai.Scope.new() |> Rhai.Scope.push("a", 10) |> Rhai.Scope.push("b", 3)
{:ok, 30} = Rhai.Engine.eval_with_scope(engine, scope, "a * b")
```
### AST
```elixir
engine = Rhai.Engine.new()
scope = Rhai.Scope.new() |> Rhai.Scope.push_constant("a", 10) |> Rhai.Scope.push_constant("b", 3)
{:ok, %Rhai.AST{} = ast} = Rhai.Engine.compile_with_scope(engine, scope, "a * b")
{:ok, 30} = Rhai.Engine.eval_ast(engine, ast)
# AST can be shared between engines
task = Task.async(fn -> Rhai.Engine.eval_ast(Rhai.Engine.new(), ast) end)
{:ok, 30} = Task.await(task)
```
### Raw Engine
```elixir
engine = Rhai.Engine.new_raw()
# Returns an error since BasicArrayPackage is not registered
{:error, {:function_not_found, _}} = Rhai.Engine.eval(engine, "[1, 2, 3].find(|x| x > 2)")
# Please refer to https://rhai.rs/book/rust/packages/builtin.html for more information about packages
engine = Rhai.Engine.register_package(engine, :basic_array)
{:ok, 3} = Rhai.Engine.eval(engine, "[1, 2, 3].find(|x| x > 2)")
```
### Extending rhai_rustler with external native Rust modules
`rhai_rustler` utilizes the `[rhai_dylib](https://github.com/rhaiscript/rhai-dylib)` library to expand the capabilities of Rhai by loading external native Rust modules. This allows users to introduce new functions, custom types, and operators.
[test_dylib_module](https://github.com/fabriziosestito/rhai_rustler/tree/main/native/test_dylib_module) serves as an example of how to create a dylib module. A [dummy rustler module](https://github.com/fabriziosestito/rhai_rustler/blob/main/test/support/test_dylib_module.ex) is employed to trigger the compilation process. This same approach can be adopted in real-world projects, such as when distributing the dylib module as a Hex package.
## Type conversion table
Elixir Types are converted to Rhai types (and back) as follows:
| Elixir | Rhai |
| ------------------------------- | --------------------- |
| integer() | Integer |
| float() | Float |
| float() | Decimal |
| bool() | Boolean |
| String.t() | String |
| String.t() | Char |
| list() | Array |
| tuple() | Array |
| %{ String.t() => Rhai.Any.t() } | Object map |
| nil() | Empty |
| pid() | Empty (not supported) |
| ref() | Empty (not supported) |
| fun() | Empty (not supported) |
| map() | Empty (not supported) |
## Rustler precompiled
By default, **you don't need the Rust toolchain installed** because the lib will try to download
a precompiled NIF file.
In case you want to force compilation set the
`RHAI_RUSTLER_FORCE_BUILD` environment variable to `true` or `1`.
Precompiled NIFs are available for the following platforms:
- aarch64-apple-darwin
- x86_64-apple-darwin
- x86_64-unknown-linux-gnu
- x86_64-unknown-linux-musl
- arm-unknown-linux-gnueabihf
- aarch64-unknown-linux-gnu
- aarch64-unknown-linux-musl
- x86_64-pc-windows-msvc
- x86_64-pc-windows-gnu
### Release flow
Please follow [this guide](https://hexdocs.pm/rustler_precompiled/precompilation_guide.html#the-release-flow) when releasing a new version of the library.
## License
This library is licensed under Apache 2.0 License. See [LICENSE](LICENSE) for details.
## Links
- [rhai](https://github.com/rhaiscript/rhai) The Rust crate doing most of the dirty work.
- [RustlerPrecompiled](https://github.com/philss/rustler_precompiled) Use precompiled NIFs from trusted sources in your Elixir code.
- [NimbleLZ4](https://github.com/whatyouhide/nimble_lz4) Major inspiration for the RustlerPrecompiled GitHub actions workflow and general setup.
