CrRuby

CrRuby is a high-level language designed to be Ruby-compatible while adding optional static typing, a compilation-based backend, and modern concurrency primitives. It aims to deliver faster runtime performance and safer code without sacrificing Ruby's readability or ecosystem, with syntax and libraries that resemble Ruby and support for common gems and idioms.

CrRuby emerged from collaborative discussions in the Ruby community in the early 2020s. Early releases emphasized a sound type system and a bridge to interoperate with CRuby, the reference Ruby implementation. Subsequent versions expanded tooling, added an LLVM-backed native backend, and broadened library compatibility to ease porting of existing projects.

Its core design centers on an optional static type system with inference, featuring parametric generics and union types. Developers may add type annotations incrementally, enabling compile-time checks while preserving Ruby's dynamic style. CrRuby can compile to native code for performance-critical modules or run on a JIT-based runtime.

CrRuby emphasizes interoperability with the wider Ruby ecosystem. It provides a compatibility layer for Ruby gems and standard library code, and supports calling CRuby libraries through a foreign function interface. The project also offers tooling for cross-compiling and packaging, helping teams move existing Ruby projects toward mixed Ruby/CrRuby codebases.

The project remains a niche option in the Ruby ecosystem, cited for potential performance gains and gradual typing. Critics cite startup costs, occasional gem compatibility gaps, and ongoing maturation needs. Adoption depends on project requirements, team familiarity, and available tooling and libraries.

CrRuby should not be confused with CRuby, the reference implementation of Ruby, but is positioned as a complementary option for developers seeking stronger typing and performance while maintaining Ruby's familiar syntax.