The Joy of Kotlin

6 Dealing with optional data

In this chapter

• The null reference or “the billion dollar mistake”
• Alternatives to null references
• Developing an Option data type for optional data
• Applying functions to optional values
• Composing optional values

Representing optional data has always been a problem in computer programs. The concept of optional data is simple. In everyday life, it’s easy to represent the absence of something when this something is stored in a container—whatever it is, it can be represented by an empty container. For example, an absence of apples can be represented by an empty apple basket. The absence of gasoline in a car can be visualized as an empty gas tank. But representing the absence of data in computer programs is a little ...