Rustler: Bridging Elixir and Rust with Sonny Scroggin

Jun 26, 2025

Sonny Scroggin, a member of the Rustler Core Team and an expert in high-performance applications, joins Sundi Myint and Charles Suggs for an engaging discussion. They explore the seamless integration of Rust and Elixir, focusing on Native Implemented Functions (NIFs) for CPU-intensive tasks. Sonny shares insights on when to use NIFs versus other approaches, emphasizing Rust's memory safety. Exciting future developments for Rustler, including asynchronous NIF interfaces, are highlighted, alongside the enduring strengths of Elixir's dynamic model.

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INSIGHT

Rust as High-Level Low-Level Language

Rust manages memory safety at compile time, preventing common bugs like use-after-free errors.
It offers low-level control with high-level safety, making it unique among system languages like C and C++.

ANECDOTE

JWT NIF at Bleacher Report

Sonny recalled building a NIF for JWT signing at Bleacher Report to handle spiky traffic efficiently.
The Rust NIF significantly improved JWT signing speed, reducing CPU saturation during high demand.

ADVICE

When to Choose NIFs

Reach for Rustler NIFs only when needing to optimize CPU-intensive operations.
Prefer ports or external services when performance needs are lower or when isolation from the BEAM is advantageous.

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Rustler Core Team Member Sonny Scroggin joins Elixir Wizards Sundi Myint and Charles Suggs. Rustler serves as a bridge to write Native Implemented Functions (NIFs) in Rust that can be called from Elixir code. This combo leverages Rust's performance and memory safety while maintaining Elixir's fault tolerance and concurrency model, creating a powerful solution for CPU-intensive operations within Elixir applications.

Sonny provides guidance on when developers should consider using NIFs versus other approaches like ports or external services and highlights the considerations needed when stepping outside Elixir's standard execution model into native code.

Looking toward the future, Sonny discusses exciting developments for Rustler, including an improved asynchronous NIF interface, API modernization efforts, and better tooling. While Rust offers tremendous performance benefits for specific use cases, Sonny emphasizes that Elixir's dynamic nature and the BEAM's capabilities for distributed systems remain unmatched for many applications. Rustler simply provides another powerful tool that expands what developers can accomplish within the Elixir ecosystem.

Key topics discussed in this episode:

Rust as a "high-level low-level language" with memory safety
NIFs (Native Implemented Functions) in the BEAM virtual machine
Rustler's role simplifying Rust-Elixir integration with macros
CPU-intensive operations as primary NIF use cases
Beam scheduler interaction considerations with native code
Dirty schedulers for longer-running NIFs in OTP 20+
Memory safety advantages of Rust for NIFs
Development workflow using Mix tasks for Rustler
Common pitfalls when first working with Rust
Error handling improvements possible with Rustler NIFs
Differences between ports, NIFs, and external services
Asynchronous programming approaches in Rust versus Elixir
Tokyo runtime integration for asynchronous operations
Static NIFs for mobile device compatibility
Upcoming CLI tooling to simplify Rustler development
Rustler's API modernization efforts for better ergonomics
Thread pool sharing across multiple NIFs
Wasm integration possibilities for the BEAM
Compile-time safety versus dynamic runtime capabilities
Performance considerations when implementing NIFs
Compiler-assisted memory management in Rust
Automatic encoding/decoding between Rust and Elixir types
The importance of proper error handling
Real-world application in high-traffic authentication servers
Community resources for learning Rustler

Links mentioned:

https://github.com/rusterlium/rustler
https://github.com/rust-lang/rust
https://www.angelfire.lycos.com/
https://www.webdesignmuseum.org/flash-websites
https://www.php.net/
https://xmpp.org/
https://jabberd2.org/
Geocities: https://cybercultural.com/p/geocities-1995/ (fun fact: when you search Geocities on Google, the results page is in Comic Sans font.)
https://bleacherreport.com/
https://hexdocs.pm/jose/readme.html
https://github.com/rust-lang/rust-bindgen
Erlang Ports: https://www.erlang.org/doc/system/c_port.html
Erlang ETFs (External Term Format): https://www.erlang.org/doc/apps/erts/erl_ext_dist.html
Elixir gRPC https://github.com/elixir-grpc/grpc
gRPC (“Remote Proceduce Call”): https://grpc.io/
dirty_cpu.ex https://github.com/E-xyza/zigler/blob/main/lib/zig/nif/dirty_cpu.ex
ets https://www.erlang.org/doc/apps/stdlib/ets.html
Mnesia https://www.erlang.org/doc/apps/mnesia/mnesia.html
VPPs (Virtual Power Plants): https://www.energy.gov/lpo/virtual-power-plants
https://nixos.org/
WASM WebAssembly with Elixir: https://github.com/RoyalIcing/Orb
Rust Tokio https://tokio.rs/

Getting Started:
https://hexdocs.pm/rustler/0.17.0/Mix.Tasks.Rustler.New.html
https://rustup.rs/

Special Guest: Sonny Scroggin.