Instaparse Live

Built on the work of Alex and Mark Engelberg (instaparse) and Lucas Bradstreet (instaparse-cljs), Instaparse Live continues to follow the question: What if context-free grammars were as easy to use as regular expressions?

(You can try it here)

When I started working with Instaparse I knew nothing about writing a parser, and I made frequent mistakes. Excited by the tool but frustrated by the lack of an instant feedback cycle, I made a quick instant-preview page in ClojureScript that I found useful. After asking the creator of instaparse-cljs if this had been done before, I decided to build the more polished version that you are now visiting.

Part of my motivation was the parsing problem, but I also wanted more experience using CodeMirror, Marijn Haverbeke's excellent in-browser code editor, from ClojureScript. I think there is a grand future for special-purpose browser-based coding environments. In Instaparse Live, since programmers are my audience, instead of building a graphical interface for parsing options I let you edit the options as a Clojure map inside an editor:

A software designer could use Instaparse to design a small language to expose functionality to power users, write a simple CodeMirror mode for it (I wrote a limited ebnf mode in a few lines of javascript), and then embed a CodeMirror instance in the application - not entirely unlike how Excel gives power users formulas.