1.3 Functions

The notion of “expression” includes functions and all that goes into writing and using them. The syntax of their definition varies significantly among programming languages, unlike simple arithmetic expressions. In words, I can say

The function maximum(x, y) returns x
if it is larger than y. Otherwise, it returns y.

Let’s consider this informal definition.

• It has a descriptive name: maximum.
• There are two variables within parentheses: x and y. These are the parameters of the function.
• A function may have zero, one, two, or more parameters. To remain readable, it shouldn’t have too many.
• When we employ the function as in maximum(3, -2) to get the larger value, we call the function maximum on the arguments 3 and -2.
• To repeat: x and y are parameters, and 3 and -2 are arguments. However, it’s not unusual...