Blobs is a diagram editor for directed graphs. It is written in
Haskell, using the platform-independent GUI toolkit wxHaskell. It
is a community project at a fairly early stage of development - you
are encouraged to get involved and improve it!
Blobs is a front-end for drawing and editing graph diagrams. You
must add your own back-end engine if you want it to do some
analysis or processing of the graph.