Proxy 
Swift package that implements mutable and immutable proxy objects through @dynamicMemberLookup,
and lazy proxy-based object builders (Partials).
TL;DR
struct Foo {
let constant = 1337
var label = "Initial"
var number = 42
}
var immutableProxy = ImmutableProxyRef(of: Foo())
immutableProxy.label // "Initial"
immutableProxy.number // 42
var mutableProxy = ProxyRef(of: Foo())
mutableProxy.label // "Initial"
mutableProxy.label = "New"
mutableProxy.label // "New"
var partial = Partial(createInstanceClosure: { Foo() })
partial.label = "Bar"
partial.number = 1
let obj = partial.build()
obj.label // "Bar"
obj.number // 1