wxHaskell is a portable and native GUI library for Haskell.
The goal of the project is to provide an industrial strength GUI
library for Haskell, but without the burden of developing (and
maintaining) one ourselves.

wxHaskell is therefore built on top of wxWidgets - a comprehensive C++
library that is portable across all major GUI platforms; including
GTK, Windows, X11, and MacOS X. Furthermore, it is a mature library
that supports a wide range of widgets with the native look-and-feel,
and it has a very active community.

Since the core interface is generated automatically from the wxEiffel
binding, about 90% of the wxWidgets functionality is already
supported, excluding more "exotic" widgets like dockable windows. Most
work is currently directed into writing a Haskellized version of the
wxWidgets API. The library currently supports Windows, GTK (Linux) and
MacOS X.