Scala for the Impatient, 3rd Edition

Chapter 17. Type Parameters

Topics in This Chapter L2

• 17.1 Generic Classes

• 17.2 Generic Functions

• 17.3 Bounds for Type Variables

• 17.4 Context Bounds

• 17.5 The ClassTag Context Bound

• 17.6 Multiple Bounds

• 17.7 Type Constraints L3

• 17.8 Variance

• 17.9 Co- and Contravariant Positions

• 17.10 Objects Can’t Be Generic

• 17.11 Wildcards

• 17.12 Polymorphic Functions

• Exercises

In Scala, you can use type parameters to implement classes and functions that work with multiple types. For example, an Array[T] stores elements of an arbitrary type T. The basic idea is very simple, but the details can get tricky. Sometimes, you need to place restrictions on the type. For example, to sort elements, T must provide an ordering. Furthermore, if the parameter type varies, ...