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