This package is provides the Happlets API that is common to all Happlet
back-end provider libraries. Along with this package, it is necessary to
install a back-end library such as 'happlets-lib-gtk'. Currently Gtk+
version 2 with a Cairo-based canvas is the only back-end available. Gtk+
version 3, Xlib, SDL2, GLUT, and (possibly) Wayland back-ends are all
feasible and may be implemented in the future.
The goal of the Happlets project is to allow you to create very simple,
thread-safe applications that contain nothing more than a single window
with a drawing canvas that can respond to user input events, like mouse
clicks, key-presses, or frame animation events. The intention is to
create a minimal programming platform for small, single-purpose
graphical applications which simply displays some interactive graphic,
for example a plot of some data, or a simple game. Naturally, the
Happlet program can be arbitrarily complex, but it may be better to
consider other, FRP-based solutions if managing events becomes too
difficult.
A happlet back-end provider may provide additional widget API functions,
but using these APIs will result in your applet being dependent on the
specific back-end and will thus not be as portable as programming for
the "happlets" package alone. Happlets aims to achieve a balance between
being as minimal as possible, but still provide enough graphics drawing
primitives to be useful for the widest range of possible applications.
The Gtk+ v2 back-end provider can be downloaded from this link:
https://hackage.haskell.org/package/happlets-lib-gtk
