Obligatory NL ambiguity example.

The grammar is small and simple, but exhibits prepositional phrase attachment
ambiguity.

Example: "the man saw the race with a telescope"
Can be bracketed as the following
 (a) "the man saw (the race with a telescope)"
 (b) "(the man saw the race) with a telescope"

Note: the "lexicon" contains some ambiguous words too - see if you can extend
the grammar so this comes into play.


"make run" to run the test case.

For Hugs, load up Hugs.lhs - it is a simplified version, with entry point 
"test :: String -> IO ()"