Functional Swift Cheat Sheet

Functional.swift

// Product of list
func product(list: [Double]) -> Double {
    return list.reduce(1, combine: *)
}

// Sum of list
func sum(list: [Int]) -> Int {
    return list.reduce(0, combine: +)
}

// Sum of filtered list
var sum = range(1..<1000).filter { ($0 % 3 == 0) || ($0 % 5 == 0) }.reduce(0, combine: +)

// Prime numbers generator
func primes(numbers: [Int]) -> [Int] {
    guard !numbers.isEmpty else { return [] }
    let first = numbers[0]
    return [first] + primes(numbers[1..<numbers.count].filter { $0 % first > 0 })
}