rustler
A safe Rust library for creating Erlang NIFs that prevents crashes in the BEAM VM.
What is rustler?
Rustler is a library for writing Erlang Native Implemented Functions (NIFs) in safe Rust. It enables developers to extend Erlang and Elixir applications with high-performance Rust code while ensuring the stability of the BEAM virtual machine. The library handles the complex boilerplate of Erlang interoperability, making it accessible to integrate Rust's performance benefits into Erlang/Elixir ecosystems.
Erlang and Elixir developers who need to write performance-critical native extensions or integrate existing Rust libraries into their BEAM-based applications.
Developers choose Rustler because it prioritizes safety by preventing Rust code from crashing the BEAM VM, and it simplifies interoperability by handling encoding/decoding boilerplate and providing easy attribute-based type composition.
Overview
Safe Rust bridge for creating Erlang NIF functions
Use Cases
Best For
- Writing safe, high-performance native extensions (NIFs) for Erlang or Elixir applications.
- Integrating existing Rust libraries or algorithms into the BEAM ecosystem without risking VM crashes.
- Creating resource objects to safely pass references to Rust structs into Erlang/Elixir code with automatic cleanup.
- Simplifying the encoding and decoding of Rust values into Erlang terms with minimal boilerplate.
- Extending Elixir applications with Rust code, as the library currently favors Elixir integration.
- Building NIFs that require compatibility with specific NIF versions (e.g., 2.15, 2.16, or 2.17) via feature flags.
Not Ideal For
- Projects requiring simple, quick extensions without Rust's compile-time overhead or NIF complexity
- Teams exclusively using pure Erlang without Elixir, as the library currently favors Elixir integration
- Applications where maintaining a separate Rust codebase adds undue operational complexity compared to optimized BEAM-native solutions
- Real-time systems sensitive to NIF scheduling delays, as native code execution can still impact BEAM scheduler behavior
Pros & Cons
Pros
Prevents Rust panics from crashing the BEAM VM by catching them before they unwind into C, a core feature highlighted in the README's safety section.
Simplifies encoding and decoding of Rust values into Erlang terms with easy function calls, reducing boilerplate as demonstrated in the minimal 'add' NIF example.
Allows making Rust structs encodable and decodable to Erlang/Elixir with a single attribute, streamlining data handling as per the type composition feature.
Safely passes references to Rust structs into Erlang code as resource objects, with automatic cleanup when no longer referenced, preventing memory leaks.
Cons
The README states the library favors Elixir over Erlang, which may result in less polished support or documentation for pure Erlang projects.
Requires careful handling of NIF version features (e.g., 2.15, 2.16) via Cargo flags and compatibility with specific OTP/Elixir versions, adding setup overhead.
Integrating Rust necessitates managing both Rust and BEAM toolchains, increasing initial configuration and ongoing maintenance compared to single-language solutions.
Frequently Asked Questions
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