I can think of two examples, only one of which is me being a smartass. Emacs has a feature called org-mode Babel that lets you write scripts where you pipe the

I can think of two examples, only one of which is me being a smartass. Emacs has a feature called org-mode Babel that lets you write scripts where you pipe the output from a block in one language to a block in any other language, but I don't think you could write a sizeable app this way. The slightly more smart-alecky answer is the command line. I work in node, and it's trivial to call an external program and then operate on the output. There's nothing stopping you from writing a program that is a single function in the language of your choice and calling it wherever you want.