Extract the juices

[abooij]

This is slowly becoming a fairly serious project, so it probably contains several pieces of code that really should be generalised and released as standalone packages. I don't know what they are, but this issue highlights the efforts to find them.

[abooij]

• The process of tying knots in XML-style data structures (although it's fairly specific) (Graphics.Sudbury.Protocol.Knot)
• Reading out potentially looping C structs (Graphics.Sudbury.CABI.Protocol)
• Unix domain sockets with fd passing (specifically being able to handle cmsgs) (Graphics.Sudbury.Socket and Graphics.Sudbury.Socket.Wayland)

[abooij]

Another new thing that we going to be doing (but aren't yet) is to generate APIs (namely the safe Haskell interface, based on a wayland XML protocol file). So perhaps we could think about doing this in a nice way. Maybe we can use ezyang's backpacks?