Learning Functional Programming in Go

Immuable Data

Immutable data structures:

• Have one state and never change
• Are simpler to construct, debug, test, and reason about
• Are side-effect free 
• Improve performance and are more scalable because they are easier to cache
• Are safer in that they prevent null pointer references
• Are thread safe
• Are always in a stable state

Since immutable data structures are never changed, that means that failures never occur during a data modification operation. When an immutable data structure is initialized it will either fail or succeed, returning a valid data structure that never changes.

In order to make changes to an immutable data structure, we must create a new tree. Suppose we want to update the value of g in the existing tree data structure ...