Crate rex 

Embedder-facing API for Rex.

Rex is a strict, statically typed, pure functional language intended to be embedded in Rust applications. Host programs provide modules and native functions, then run user-supplied Rex snippets or module files to coordinate work. The main public API is the engine module, especially Engine for configuring the runtime and Module for exposing host capabilities to Rex code.

Most embedders start with Engine::with_prelude, register one or more host modules, then evaluate a snippet or module through an Evaluator. The parser, type system, runtime value, and JSON conversion APIs are also re-exported here so an application can choose how much of the Rex pipeline it wants to control.

Minimal embedding example

use rex::engine::{Engine, EngineError, Module};

let mut engine = Engine::with_prelude(())?;
engine.add_default_resolvers();

let mut math = Module::new("host.math");
math.export("inc", |_state: &(), x: i32| {
    Ok::<i32, EngineError>(x + 1)
})?;
engine.inject_module(math)?;

let (value, typ) = engine
    .into_evaluator()
    .eval_snippet("import host.math (inc);\ninc 41")
    .await?;

assert_eq!(typ.to_string(), "i32");
assert_eq!(value.as_i32()?, 42);

For lightweight tests and command-line style integrations, eval parses, typechecks, evaluates, and converts the result to JSON in one call. Production embedders usually use Engine directly so they can register host modules, set execution bounds, inspect type information, and handle compile and evaluation errors separately.

Modules

ast

Rex abstract syntax tree types produced by the parser. Source-level syntax tree types.

engine

Compile-time and runtime APIs for embedding Rex in a Rust host program. Compile and run Rex programs from a Rust host.

json

Conversion between JSON values and typed Rex runtime values. JSON conversion helpers for runtime Rex values.

parser

Source parser entry points and parse diagnostics. Parse Rex source text into AST values.

typesystem

Hindley-Milner type inference, type representations, ADTs, and type classes. Type inference and Rex type metadata.

Functions

eval

Parse, typecheck, evaluate, and JSON-encode a Rex snippet.

Derive Macros

Rex

Derive bridge for Rust data types that should cross the Rex boundary.