it works well!

Extension Array Like Perl

extension Array {
    typealias Element = T

    mutating func scalar() -> Int {
        return Int(self.count)
    }
    
    mutating func pop() -> T? {
        if self.count == 0 { return nil }
        let removed = self.removeAtIndex(self.endIndex.predecessor())
        return removed
    }
    
    mutating func push(values: T...) -> [T] {
        self.splice(values, atIndex: self.endIndex)
        return self
    }
    
    mutating func shift() -> T? {
        if self.count == 0 { return nil }
        let removed = self.removeAtIndex(self.startIndex)
        return removed
    }
    
   mutating func unshift(values: T...) -> [T] {
//        self.insert(values.reverse(), atIndex: self.startIndex) // Error "Array<T> is not convertible to 'T'"
        for v in values.reverse() { // it works but I wonder why...
            self.insert(v, atIndex: self.startIndex)
        }
        return self
    }
}
// Use like bellow
var a :Array = ["String", "String2", "String3" ]
a.scalar()
a.splice(["splice1", "splice2"], atIndex: 1)
a.count

a.unshift("one", "two") // 配列の挿入
a.unshift("zero") // 1要素の挿入

a.count
a.push("push", "push2") // 配列の追加
a.push("push3") // 1要素の追加
a[2]
a
a.count
a.shift()   // 先頭の値を取り出し
a.pop()     // 末尾の値の取り出し
a.count

// for Int
var b :Array = [4, 7, 8 ]
b.splice([5, 6], atIndex: 1)
b.unshift(1, 2) // 配列の挿入
b.unshift(0)    // 1要素の挿入
b.push(9, 10)   // 配列の追加
b.push(11)      // 1要素の追加
b[2]            // 2
b               // [0,1,2,3,4,5,6,7,8,9,10,11]
b.count         // 11
b.shift()       // 先頭の値を取り出し
b.pop()         // 末尾の値の取り出し
b.count         // 9

// We can't mix the Types in Swft's Array
//var c :Array = [a, b, 0]    // Error "'Int' is not identical to 'String'"

with typealias, it just works.

//class ArrayLikePerl {
extension Array {
    typealias Element = T

    //    init(T){ // does it need?
    //        func T(){}
    //    }

    mutating func scalar() -> Int {
        return Int(self.count)
    }

    mutating func pop() -> T? {
        if self.count == 0 { return nil }
        let removed = self.removeAtIndex(self.endIndex.predecessor())
        return removed
    }

    mutating func push(values: T...) -> [T] {
        //        for v in values {
        self.splice(values, atIndex: self.endIndex) // (v, atIndex: self.endIndex) //Error "T is not identical to protocol<>"
        //        }
        return self
    }

    mutating func shift() -> T? {
        if self.count == 0 { return nil }
        let removed = self.removeAtIndex(self.startIndex)
        return removed
    }

    mutating func unshift(values: T...) -> [T] {
        for v in values.reverse() {
            self.insert(v, atIndex: self.startIndex.successor())  //Error "protocol<> is not convertible to T"
        }
        return self
    }
}

@tottokotkd: thanks very much!
It worked like what I thought without self.startIndex.successor()