5 Operations and comparisons: Seeing processes as functions

Addition of numbers is a process that one would expect a computer to be able to perform. Now we write the result of adding the numbers 5 and 2 as 5 + 2, for example. The symbol +, which represents the process of addition, appears between the two numbers being added. This is known as infix notation. Infix notation may be used for processes that combine two data items of the same type. Addition, subtraction and multiplication of numbers are familiar examples. We also use infix notation when writing a comparison of the size of two numbers, such as 5 < 9.
In this section, we shall show that a process such as addition of numbers is a function. Perhaps more surprisingly, a process such as < can also be seen as a function. This perception is a necessary preliminary to seeing how such a process can be implemented by a computer.