Generally encountered side effects
In this section, we will talk more about the side effects commonly encountered in programs. Some of them we have already introduced, and others you may already know from your everyday programming. However, it is crucial for you to pay particular attention to such side effects, because this way, you learn to distinguish them in an ordinary program.
When writing programs (and when living our lives in general), very often, we get used to things without even paying attention to them. Certain things may be a source of headaches and problems, and the first step to resolving the problems is to name the things that cause them.
As functional programming aims to eliminate side effects, it is reasonable for us to name some of the side effects that cause pain.
Error
The first effect we will be discussing is the effect of an error. An error is produced when something goes wrong in your program. In imperative languages, it is usually modeled by an exception. An exception...
