Rhai - Embedded Scripting for Rust

Rhai is an embedded scripting language and evaluation engine for Rust that gives a safe and easy way to add scripting to any application.

Supported targets and builds

Easy-to-use language similar to JS+Rust with dynamic typing.
Tight integration with native Rust functions and types, including getters/setters, methods and indexers.
Freely pass Rust variables/constants into a script via an external Scope.
Easily call a script-defined function from Rust.
Fairly low compile-time overhead.
Fairly efficient evaluation (1 million iterations in 0.25 sec on a single core, 2.3 GHz Linux VM).
Relatively little unsafe code (yes there are some for performance reasons, and most unsafe code is limited to one single source file, all with names starting with "unsafe_").
Re-entrant scripting engine can be made Send + Sync (via the [sync] feature).
Sand-boxed - the scripting engine, if declared immutable, cannot mutate the containing environment unless explicitly permitted (e.g. via a RefCell).
Rugged - protection against malicious attacks (such as stack-overflow, over-sized data, and runaway scripts etc.) that may come from untrusted third-party user-land scripts.
Track script evaluation progress and manually terminate a script run.
Function overloading.
Operator overloading.
Organize code base with dynamically-loadable modules.
Scripts are optimized (useful for template-based machine-generated scripts) for repeated evaluations.
Support for minimal builds by excluding unneeded language features.

See The Rhai Book for details on the Rhai scripting engine and language.