name: crystal description: Crystal Ruby-like syntax with static typing. Use for .cr files.

Crystal

Crystal compiles to native code (using LLVM) but looks exactly like Ruby. v1.12 continues improving Windows support and parallelism.

When to Use

• Performance sensitive Rubyists: Porting heavy Ruby scripts to Crystal for 50x speedup.
• Microservices: Low memory footprint compared to JVM/Ruby.
• CLI Tools: Fast startup and execution.

Core Concepts

Fibers

Lightweight concurrency (like Go routines). spawn { ... }.

Macros

Generate code at compile time (like Zig/Lisp).

Union Types

String | Int32. The compiler handles the branching.

Best Practices (2025)

Do:

• Use strict types in APIs: Help the compiler with def foo(x : Int32).
• Use shards: Dependency manager.
• Use -Dpreview_mt: To test multithreading capabilities.

Don't:

• Don't use eval: Crystal is compiled, there is no runtime eval.

References

• Crystal Lang