Oh that's nothing. In Java I came up with a way to pass config options using method references as keys, so you can write something like: createFoo(with(FooOp

Oh that's nothing. In Java I came up with a way to pass config options using method references as keys, so you can write something like: createFoo(with(FooOptions::enable, true), with(FooOptions::size, 7)); And processing the options involves serialising each method reference to work out what it is!