Falling2d is a basic 2d Rigid Bodies Physics Engine aimed to be used in real-time. Its actually only a set of aliases and definitions of simple 2d constructs needed by the falling generic Physics Engine (https://github.com/sebcrozet/falling)
See the Falling2d-examples repository for demos: https://github.com/sebcrozet/falling2d-examples
Falling2d is not yet available on hackage, thus you will have retrieve it from here. We strongly encourage the use of cabal for the compilation routine.
$ git clone git://github.com/sebcrozet/falling2d.git
$ cd falling2d
$ cabal install