Chapter Five
Names, Bindings, Type Checking, and Scopes

Imperative programming languages are abstractions of von Neumann computer architecture.
Primary components of von Neumann:
    1. memory: store data & instructions
    2. CPU: provide operations to modify the contents of memory.

A variable is an abstraction of a memory cell

Variables are characterized by a collection of attributes
which are

• Names - not all variables have them
• Address - the memory address with which it is associated
• Value
• Type
• Lifetime
• Scope
• Scope and Lifetime

Categories of Variables by Lifetimes

Type Checking

Static Scoping Rule vs. Dynamic Scoping Rule