Ruby vs. F# vs. Hack

Ruby is a language of careful balance. Its creator, Yukihiro “Matz” Matsumoto, blended parts of his favorite languages (Perl, Smalltalk, Eiffel, Ada, and Lisp) to form a new language that balanced functional programming with imperative programming.

F# is a mature, open source, cross-platform, functional-first programming language. It empowers users and organizations to tackle complex computing problems with simple, maintainable and robust code.

Hack provides instantaneous type checking via a local server that watches the filesystem. It typically runs in less than 200 milliseconds, making it easy to integrate into your development workflow without introducing a noticeable delay.