Convert a property into a function (a setter) so the value can be set as part of a function pipeline, or partially applied so the property can be set in response to specific events.

Setter.swift

class Test {
    var greeting = "Hello, playground"
}

let test = Test()

func setter<O: AnyObject, V>(_ obj: O, _ keyPath: ReferenceWritableKeyPath<O, V>) -> (V) -> () {
    { [weak obj] value in obj?[keyPath: keyPath] = value }
}

// Partial application
func papply<A, B>(_ a: A, _ f: @escaping (A) -> B) -> () -> (B) {
    { f(a) }
}

let f = papply("Wow", setter(test, \.greeting))

test.greeting // "Hello, playground"
f()
test.greeting // "Wow"