These are sketches for a collaborative editor closely following
suggestions taken from the paper "Real time group editors without
Operational transformation" by Oster, Urso, Molli and Imine.

Using the JSHash module, it is possible to use a Javascript array as a 
typed hash in Haskell.

Insertion and Deletion are working, I'm still thinking about how to 
represent and communicate markup and how to highlight each client with 
an own background color. This will probably interfere with caret 
handling.

There's still bugs in the code, I'm thinking about using coq to check
the critical portions (Editor.hs, Visible.hs etc.), but this would be
hard.

I prepared a dequeue on the server side, which is going to get written
into a RDBMS, so any inbetween-states can be reconstructed. However, I
did not get HaskellDB to run so far.