Property as method and overriding in Swift (impossible for method)

foo.swift

import Cocoa

class A {
    var foo : () -> String
    var baz : Int
    
    init () {
        func _foo () -> String {
            return "halo"
        }

        self.foo = _foo;
        self.baz = 1
    }
    
    func jaz () -> String {
        return "jazz"
    }

}

func _bar () -> String {
    return "benjour"
}

var b = A()
b.foo()
//b.jaz = _bar // Cannot assign to 'jaz' in 'b'
b.foo = _bar
b.foo()