typealias CallbakFunc = (Void) -> Void
func testEqualsfunc() {

var a:CallbakFunc = {}
var b:CallbakFunc = {}
var c:CallbakFunc = {}

var list:[CallbakFunc] = []

list.append(a)
list.append(b)
list.append(c)

for x in list {
if x == a { // Swift compile Error : Binary operator '==' cannot be applied to operands of type '() -> ()' and 'CallbakFunc'
println("a is hit")
}
}
}

上記Errorの解決方法をご教授下さい