MinMax.swift

MinMax.swift

extension Sequence {
    @warn_unqualified_access
    public func min<T:Comparable>(by: (Element) throws -> T) rethrows -> Element? {
        return try self.min { try by($0) < by($1) }
    }
    @warn_unqualified_access
    public func max<T:Comparable>(by: (Element) throws -> T) rethrows -> Element? {
        return try self.max { try by($0) > by($1) }
    }
}

struct S {
    let a: Int
    let b: Int
}
let items:[S] = [S(a:1, b:2), S(a:2, b: 5)]
let minimum = items.min { $0.a + $0.b }               // Bit shorter
let minimum2 = items.min { $0.a + $0.b < $1.a + $1.b}