Write programs that are clear to both the reader and the compiler.

The first and foremost general principle of programming is clarity. From clarity comes the ability to test, to reuse, and to audit. One simple test is whether you believe you will be able to understand the code if you come back to it a year later.

Of course, you write programs to have the computer calculate something for you. And you know that the computer must be told exactly what to compute. Your program must completely and correctly specify what is to be computed.

If you are making a numerical calculation, you likely have some consideration for the efficiency of your calculation. The best way to gain efficiency is to first choose an efficient algorithm and then to write simple, clear, and logical code to implement it. Compared with more complex code, it is easier to understand and easier for the compiler to optimize.

In addition to writing code for the computer, you are also writing code for humans, yourself included. The purpose of the calculations and the methods used to do so must be clear.

To achieve these goals, write code that is as simple as possible. Use white space to aid your eye in following the calculation specified by the source code. Comment what cannot be understood from the code itself. The rules in this book follow from these ideas.