I'm happy to announce the release of UISF on Hackage! http://hackage.haskell.org/package/UISF UISF provides an arrowized FRP library for graphical user interfaces. It stems from work done on Euterpea (http://haskell.cs.yale.edu/euterpea/), and is built atop GLFW. One of the neat things about UISF is how it behaves with ArrowChoice. Specifically, one can create dynamic arrows so long as they are *predictably* dynamic. This means that it is possible to have widgets activate, deactivate, and even replicate without resorting to switch. If you're interested in playing around with it, feel free to take a look at the example files, some of which are pretty well documented (note that there are more than just the two displayed on the hackage page). Do let us know about comments you have and bugs you find. -Daniel