Uses $a for variables exclusively. (Fixes #41)

--HG--
extra : amend_source : c47ce27d981905490a30fca71ba7400e1fbf18f0
Support partial application.
Supports multiple arguments in patterns.

--HG--
extra : amend_source : 10849009a49c584f1d5cfb6469f229c10ed3eee1