The simple lexer and the complete parser was made using a parser combinator library called JSParse and it worked out fine except that it does not keep track of line numbers, columns or which parser that failed so it is really hard to get any good error messages. There were also a couple of bugs in the butnot-parser and in the caching for the choice parser. I managed to fix both of them and the functioning version can be found at our git repository.
We do not support type classes at the moment but we will most likely fix that in the two coming weeks as we really want them in the final presentation of the project.
I have also put up an online demo at http://hiji.tinyrocket.se that works in firefox and chrome but internet explorer remains untested. The demo has a small part of the standard prelude library the definition of which can be found here http://hiji.tinyrocket.se/hs/Prelude.hs
Have a nice day