OCaml

OCaml v5 brings Multicore support to the language, removing the Global Interpreter Lock (GIL). It combines functional safety with imperative speed.

When to Use

• Compilers: Rust, Haxe, and Flow are written in OCaml.
• Financial Trading: Jane Street uses OCaml for everything.
• Formal Verification: Coq proof assistant is OCaml.

Core Concepts

Strong Static Types

Inference is so good you rarely write types.

Modules (Functors)

Parametrized modules (functions that return modules).

Effects (v5)

Algebraic Effects for concurrency (e.g., Eio).

Best Practices (2025)

Do:

• Use dune: The standard build system.
• Use opam: The package manager.
• Use Eio: The modern async I/O library for OCaml 5.

Don't:

• Don't use Threads directly: Use domains/effects for parallelism.

References

• OCaml.org