Extensions for Swift's Array type

ArrayExtensions.swift

extension Array {
    
    // Usage: [1,2,3,4].shifted(by: 2) --> [3,4,1,2] or "hello".shifted(by: -1) --> "elloh"
    func shifted(by shiftAmount: Int) -> Array {
        guard self.count > 0, (shiftAmount % self.count) != 0 else { return self }
        let moduloShiftAmount = shiftAmount % self.count
        let effectiveShiftAmount = moduloShiftAmount < 0 ? moduloShiftAmount + self.count : moduloShiftAmount
        let shift: (Int) -> Int = { return $0 + effectiveShiftAmount >= self.count ? $0 + effectiveShiftAmount - self.count : $0 + effectiveShiftAmount }
        return self.enumerated().sorted(by: { shift($0.offset) < shift($1.offset) }).map { $0.element }
    }
    
}