IMP is a monadic style implementation of the semantics of the (very simple)
language IMP, "plain" the implementation with explicit passing of state.
                                                                                
The semantics of the IMP-language is presented in the book:

  "The Formal Semantics of Programming Languages" by Glynn Winskel
  (1993, The MIT Press).

For more details on monads, see Philip Wadler's page on:

 http://cm.bell-labs.com/cm/cs/who/wadler/topics/monads.html#combining-monads

Author:	Markus Mottl <markus.mottl@gmail.com>
WWW:	http://www.ocaml.info/home/ocaml_sources.html