Memoized parser combinators for Caterwaul 1.1. Unlike previous implementations,
this one allows you to parse things that are nonlinear. For example, you can
"parse" Caterwaul syntax trees to do things like nondeterministic searches.
This arises from the fact that combinatory parsers are really just incremental
functions and various sequential modifications of them. (More about this in the
source documentation.)