Problem Statement
How would you create a custom higher-order function in Swift that takes a closure and returns another function? Provide an example and explanation.
Explanation
You create a function that either accepts a closure as an argument, or returns a closure, or both. For example: `func times(_ n: Int) -> ((Int) -> Int) { return { x in return x * n } }`. /n/n Here `times(3)` returns a function that multiplies its argument by 3. This illustrates returning a function. You could also accept a function argument: `func applyTwice<T>(_ f: (T) -> T) -> ((T) -> T) { return { x in f(f(x)) } }`. /n/n This demonstrates higher-order behaviour. Creating and using custom higher-order functions in Swift shows deeper mastery beyond standard `map`/`filter`.
Practice Sets
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