Using Swift reduce() and min() to find minimum value in an array

minReduce.swift

struct Value {
    let num: Int

    init(_ n: Int) { num = n }
}

let a = [Value(3), Value(2), Value(1), Value(4), Value(5)]

let min1: Value = a.reduce(Value(Int.max)) {
    ($0.num < $1.num) ? $0 : $1
}

println("min1 is \(min1.num)")


// Use the standard library "min" operator

// Have to make Value conform to Comparable
extension Value: Comparable {}

func ==(lhs: Value, rhs: Value) -> Bool {
    return lhs.num < rhs.num
}

func <(lhs: Value, rhs: Value) -> Bool {
    return lhs.num < rhs.num
}

let min2: Value = a.reduce(Value(Int.max), combine: min)

println("min2 is \(min2.num)")


// Use map and reduce with min

let min3: Int = a.map{ $0.num }.reduce(Int.max, combine: min)
println("min3 is \(min3)")


// Lazy evaluation

let min4: Int = reduce(lazy(a).map{ $0.num }, Int.max, min)
println("min4 is \(min4)")


// Generic function to find minimum element of a sequence of Comparable items

func minElement<T : Comparable, S : SequenceType where S.Generator.Element == T>(sequence: S, initial: T) -> T {
    return reduce(sequence, initial, min)
}

let min5 = minElement(a, Value(Int.max))
println("min5 is \(min5)")

// Lexicographical ordering of strings
let minString = minElement(["one", "two", "three", "four"], "~")
println("minString is \"\(minString)\"")