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Lesson 27. Much ado about nil

After reading lesson 27, you’ll be able to

• Do something with nothing
• Understand the trouble with nil
• See how Go improves on nil’s story

The word nil is a noun that means nothing or zero. In the Go programming language, nil is a zero value. Recall from unit 2 that an integer declared without a value will default to 0. An empty string is the zero value for strings, and so on. A pointer with nowhere to point has the value nil. And the nil identifier is the zero value for slices, maps, and interfaces too.

Many programming languages incorporate the concept of nil, though they may call it NULL, null, or None. In 2009, prior to the release of Go, language designer Tony Hoare gave a presentation titled “Null References: ...