. Notes on Semantics of Smalltalk
.See /u/faculty/dick/cs320/smalltalk.semantics

.Status	PREDRAFT

A Smalltalk shares a class with similar objects
	class::objects -> classes.
	instances:: classes-> @classes= /class.
	is_instance_of::@(objects, classes)={ (x,c) | c = class(x) }.

Each object has special distinguishing values that are called its instance variable:
	instance_variables::(objects><variables)<>->values.

Classes define what set of instance variables are valid for their objects.

Classes also determine the way that their objects react to messages.  They assoicate each message selector with a method for handling it.  The set of possible messages for a class is called its protocol:
	protocol::(class><selector)<>->method.

Each method has
.List
 arguments
 local variables
 a sequence of steps
.Close.List

A message has a selector and an array of arguments;
	messages:: selector >< #objects

Sending a message to an object produces another object:
	 ____send______
	|
	| x?:objects
	| m?:messages
	|
	| result':objects
	|
	|--------------------
	|
	|  ...
	|_____________