CS 342 Lecture -*-Outline-*-

* the CLU interpreter (6.3)

	point is to see how the settors, selectors and constructor work
		also 2 part names

** Clusters
	How are clusters represented?

	CLUSTERREC on page 222
		note field names i nclrep
		exported vs. non-exported function definitions
			the non-exported ones are the privilaged operations
				settors, selectors, constructor

	FUNDEFREC p. 222
		note that constructors, selectors, and settors
			are treated specially: no body,
						settor only has name of field

	How the privilaged operations are created:
		look at ParseCluster, bottom of 548
		Pascal variable named rep is assigned list of field names
			(of CLU rep)
		on p. 549, the constructor is created, with name of the cluster
		then each field in the rep list is turned into a selector
			and a settor
		then the privialbed operations are placed in the nonexported
			part of the cluster record (cenv)

** CLU Values
	User defined vaules are distinguished from primitive values (ints)
	user values have an environment, which is the record (names+values)
		defined by the rep

	so constructor takes list of field names, and list of values (its args)
		and wraps them up into this record-like value

** Evaluation (6.3.7)
	eval has not only an environment, but a cluster record as an argument
		outside cluster: cluster record is nil
		inside cluster: allows access to nonexported operations

	application of user funtions (p. 224):
		two part names: find cluster, then get function from its
			exported list
			(note: can't access privilaged ops this way)
		one part names:
			if outside cluster, as before
			if within cluster:
				look in that cluster's exported list,
				then in nonexported list
				finally in globals

	look at how selectors and settors work (p. 225)