TypeCompose provides some classes & instances for forms of type composition. It also includes a very simple implementation of data-driven computation. I factored it out of a new implementation of Phooey. Phooey is a library for functional user interfaces. Highlights in this 0.3 release:

• Uses new TypeCompose package, which includes a simple implementation of data-driven computation.
• New Applicative functor interface.
• Eliminated the catch-all Phooey.hs module. Now import any one of Graphics.UI.Phooey.{Monad ,Applicative,Arrow}.
• Phooey.Monad has two different styles of output widgets, made by owidget and owidget’. The latter is used to implement Phooey.Applicative.
• Self- and mutually-recursive widgets now work again in Phooey.Monad. They wedge in Phooey.Arrow and Phooey.Applicative.

Phooey is also used in GuiTV, a library for composable interfaces and “tangible values”. I’ve also just updated GuiTV to 0.3, to sync with Phooey 1.0.