JSHC (JavaScript Haskell Compiler) was a bachelor's thesis project by Peter Holm and Staffan Björnesjö, done in 2011. The compiler is written entirely in JavaScript, and compiles a subset of the Haskell programming language into runnable JavaScript code. The user interface is based on Ymacs.

Try the editor live here, or read the report. Write Haskell code in the buffer and press C-x i to start the interpreter buffer and compile the code. The interpreter runs arbitrary Haskell expressions, as well as a few commands. Try :help.