Evaluation is the process by which Lisp determines the value
of an expression. Expressions are evaluated using the following
- If the expression to be evaluated is a number, T, or
NIL, its value is the expression itself.
- If the expression is (QUOTE x), its value is x.
- If the expression is a symbol, its value is the value
of the symbol (the symbol's binding).
- Otherwise, the expression must be a list that represents a
- Evaluate each argument of the function call, in left-to-right
- Call the function with the resulting values of the arguments.
- The value returned by the function is the value of the expression.