Q0
	Get code
		: In the usual place
		: svn export http://unbox.org/wisp/var/timm/10/310/src/lisp/2/c

For each of the following questions, add lines like this to "run"
	printf "\n===== 2/c/q1 ========================\n\n"
	cat myCodeThatAnswersThisQuestion.lisp
	execute
		: where "execute" is the "test" command shown below.

Q1	
	Write
		: Adapt your LISP grammar to handle attributed grammars. For such grammars,
		: some of the productions are not "(a -> RHS)" but "(a = RHS)". For
		: such rules, the rhs is a set of single atoms; e.g
		: (Article -> the a). terminal. If that rule is selected,
		: then an attribute is fixed to one of those values.
		:
		: This lets us fix strings and reuse them. To see why that is useful,
		: consider the following grammar
		:
	    : (Sentence -> (Nounphrase Verbphrase))  
	    : (Nounphrase -> (Boy))              
	    : (Nounphrase -> (Girl))           
	    : (Boy -> john ajit)
	    : (Girl -> pima barkha)
	    : (Verbphrase -> (Verb Modlist Adverb with  Nounphrase))
	    : (Verb -> runs  walks )                 
	    : (Modlist ->  () (very Modlist))
	    : (Adverb -> (quickly  slowly))))          
		:
		: Note that now we can select two boys at different parts of the
		: story.
		:
		: But, in the following grammar, once we pick a heroine/ hero then we
		: always use their name (note the use of "=" in the following).
		:
		: (Sentence -> (Nounphrase Verbphrase))  
	    : (Nounphrase -> (Boy))              
	    : (Nounphrase -> (Girl))           
	    : (Boy = john ajit)
	    : (Girl = pima barkha)
	    : (Verbphrase -> (Verb Modlist Adverb with  Nounphrase))
	    : (Verb -> runs  walks )                 
	    : (Modlist ->  () (very Modlist))
	    : (Adverb -> (quickly  slowly)))) : Sentence -> Nounphrase Verbphrase   
	Note
		: Of course, the grammar still is "broken" since in this story,
		: the someone can travel with themselves.  
		: e.g. "pima runs slowly with pima" 
		: What we need is a better
		: constraint language in our grammar such that we can specify that
		: someone cannot travel with themselves. We will build such a grammar,
		: later in the semester.
	Hint
		Working memory
			: Keep a working memory of settings in a hashtable.
			To create a hash table
				(let ((mem (make-hash-table))) ... )
			To put something into a hash table
				(setf (gethash name  mem) something)
			To test is something is NOT in a hash table
				(unless (eq :missing (gethash name mem :missing))
					;; handle missing item
				)
		Before rewriting a terminal
			: change the generation code such that before it looks up a definition
			: if checks for "if (not (eq :missing (gethash name mem :missing)))". 
			: And, if it is there, just return it.
		After rewriting a terminal
			: On return from generating a terminal, if the result is something
			: defined in as a Setting, then you have to set this Setting. 
		Reading 
			: You will also have to change how story.awk reads in productions.
			: Now, if we see "Variable = terminal", then we have to:
			: 1)	read it as if it was "Variable -> terminal"
			: 2)    add it to the hash table
	Test
		: nice -n 1 clisp -q attr.lisp
		: This code should generate enough stories till the same boy's
		: name appears twice.