OCaml
In plain terms
A practical functional language with a strong, inferred type system.
Going deeper
OCaml blends functional, imperative, and object-oriented styles with fast compilation and powerful types. It's used where correctness and performance both matter.
Under the hood
Its type inference and algebraic data types catch errors early; it influenced Rust and F# and powers some financial-trading systems.
Examples
Jane Street trading systems, compilers, the Coq prover, formal tools.
Think of it like...
Like a pragmatic mathematician who also ships fast, reliable production code.