Practical

Clojure: A modern JVM-based Lisp dialect with a focus on immutability

Haskell: An advanced, purely functional programming language

Kotlin (beta): Statically typed programming language interoperable with Java and Android

Scheme: An elegant dynamic dialect of Lisp.

Lua: A lightweight multi-paradigm scripting language.

Python 2.7: A dynamic language emphasizing readability.

Ruby: A natural dynamic object-oriented language.

Python: A dynamic language emphasizing readability.

Nodejs: Evented I/O for v8 Javascript.

Go: Statically typed yet expressive language with a focus on concurrency.

C++: A general purpose system programming language.

C++11: A general purpose system programming language.

C: Low-level and cross-platform imperative language.

C#: A Microsoft .NET programming language.

F#: A Microsoft .NET functional programming language.

Rust: A fast and safe systems programming language.

Swift: A modern general-purpose programming language from Apple.

R: a programming language and environment for statistical computing and graphics

Bash: The classic Unix shell

Crystal: Fast as C, slick as Ruby

Julia: A language for high-performance numerical analysis and computational science.

Elixir: A functional, concurrent, general-purpose programming language that runs on the Erlang VM

Nim: An imperative, multi-paradigm, compiled programming language

Dart: A general-purpose programming language used to build web, server, desktop, and mobile applications.

Reason NodeJs: Reason compiling to Nodejs (via Bucklescript)

Erlang: A general-purpose, concurrent, functional programming language

TypeScript: A typed superset of JavaScript.

Emacs Lisp (Elisp): Scripting language for the extensible text editor.

SQLite: Embedded SQL database engine.

Java: A concurrent, class-based, statically typed object-oriented language.

PHP CLI: A popular general-purpose scripting language.