gtk2hs-rpn

Adds a module to gtk2hs allowing layouts to be defined using reverse polish notation.

Adds a module Graphics.UI.Gtk.Layout.Rpn to gtk2hs. This module defines a type RPN for operators, which is an instance of Data.Monoid.Monoid class. You can combine those operators using reverse polish notation, as made popular by, say, HP calculators. There are operators for layout elements, like expanders, panes, boxes and notebooks, and for a few other widgets, like buttons and labels. You can also insert any existing gtk2hs widget in the stack.