Set operators

Abstract - CollectionOperators.md

Collection operators

let isSubset = [0,1] ⊂ [0,1,2] // true
let intersection = [0,1] ⋂ [0,2] // [0]
let union = [0,1] ⋃ [0,2] // [0,1,2]

CollectionOperators.swift

infix operator ⊂ {} // subset
func ⊂ <C : Collection where C.IndexDistance == Int, C.Iterator.Element: Equatable>(array1: C, array2: C) -> Bool {
    guard array1.count <= array2.count else { return false }
    let c = array1.filter({
        (a: C.Iterator.Element) -> Bool in
        return array2.contains({ $0 == a })
    }).count
    return c == array1.count
}

SetOperators.swift

infix operator ⋃ {}
func ⋃ <T> (left: Set<T>, right: Set<T>) -> Set<T> {
    return left.union(right)
}

infix operator ⋃= {}
func ⋃= <T> (left: inout Set<T>, right: Set<T>) {
    left.formUnion(right)
}

infix operator ⋂ {}
func ⋂ <T>(left: Set<T>, right: Set<T>) -> Set<T> {
    return left.intersection(right)
}

infix operator ⋂= {}
func ⋂= <T : Comparable>( left: inout Set<T>, right: Set<T>) {
    left.formIntersection(right)
}