Index in Array's map and reduce

gistfile1.swift

extension Array {
    func map<U>(function : (index : Int, object : T) -> U) -> [U] {
        var result = [U]()
        for i in 0..<self.count {
            result.append(function(index: i, object: self[i]))
        }
        return result
    }

    func reduce<U>(initial : U, combine : (product : U, index : Int, object : T) -> U) -> U {
        var result = initial;
        for i in 0..<self.count {
            result = combine(product: result, index: i, object: self[i])
        }
        return result
    }
  }

I think you're looking for enumerate()

map(enumerate(["a", "b", "c"])) { "\($0) \($1)" } //["0 a", "1 b", "2 c"]