Both the raw and the higher level bindings should allow you to use any aspect of the original SDL2_gfx library. Please report an issue if you encounter a bug or feel that something is missing.
cabal install sdl2-gfx
For documentation, visit Hackage.
The original SDL2_gfx documentation can also help, as the bindings are close to a direct mapping.
A small example executable is included with the library. It uses many parts of
the library to draw a chaotic jumbled mess on your screen. You can find it in
the example
directory.
cd sdl2-gfx
cabal run