This may not be helpful for you, but when I did GUI stuff with haskell I wrote the GUI part in c++ with fltk, exposed a medium-level api specific to that gui, and then call that api through the FFI. This is sort of like the web browser + backend thing, except switch c++ and fltk for javascript and the browser, and you are making synchronous FFI function calls instead of sending asynchronous JSON messages. It has worked well for me so far, but my GUIs are all simple with well defined interaction with the backend (i.e. backend says "add these 15 items" and GUI says "user selected this item"). If you have complicated interaction between backend and GUI you may get tired implementing a large API and lots of marshal/unmarshal. Of course you could still pass data via JSON or protobufs or something, and there are various tools to automate wrapping large numbers of C calls. In terms of distribution, you get a single binary and fltk is designed for static linking. You can run on X, mac, and windows, though it doesn't look like a native app on any.