Functional Programming in Swift: Principles and Practices

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Functional programming is a powerful paradigm that can lead to more predictable, testable, and maintainable code. While Swift is a multi-paradigm language, it supports functional programming concepts. In this blog post, we’ll explore the key principles of functional programming in Swift and see how they can be applied in practice.

First-class and Higher-order Functions

In Swift, functions are first-class citizens, meaning they can be assigned to variables, passed as arguments, and returned from other functions. This enables the use of higher-order functions, which are functions that take other functions as parameters or return functions.

// First-class function
let greet = { (name: String) -> String in
    return "Hello, \(name)!"
}

print(greet("Alice")) // Output: Hello, Alice!

// Higher-order function
func applyOperation (_ a: Int, _ b: Int, operation: (Int, Int) -> Int) -> Int {
    return operation(a, b)
}

let sum = applyOperation(3, 5, operation: +)
print(sum) // Output: 8
let mult = applyOperation(2, 5, operation: *)
print(mult) // Output: 10

Immutability and Pure Functions

Functional programming emphasizes immutability and pure functions. Immutable data can’t be changed after it’s created…