Swift Functional Programming - Second Edition

Optional mapping

Mapping over an array would generate one element for each element in the array. Can we map over an optional to generate non-optional values? If we have some, map it; otherwise, return none. Let's examine the following code:

func mapOptionals<T, V>(transform: (T) -> V, input: T?) -> V? {     switch input {     case .some(let value): return transform(value)     case .none: return .none     } } 

Our input variable is a generic optional and we have a transform function that takes input and transforms it into a generic type. The result will be a generic optional type. In the function body, we use pattern matching to return the respective values. Let's test this function:

class User {     var name: String? } 

We create a class named User with ...