Heroku : language (web framework) support

https://blog.heroku.com/archives/2011/8/3/polyglot_platform
https://devcenter.heroku.com/categories/language-support
http://en.wikipedia.org/wiki/Read%E2%80%93eval%E2%80%93print_loop


Ruby/Java/Python/Clojure/Scala/Node.js/Play

[Note] REPL : A read–eval–print loop (REPL) is a simple, interactive computer programming environment.