There is an interesting story here that I wish was told in more details somewhere on the internet (currently I just have some partial guesses from listening to JuliaCon talks). It seems some of these (awesome) properties arose very organically after experimentation, not by having a committee of theorists define the properties the language should have. This has led to a couple of minor inconsistencies to be ironed out, however computer scientists (like the authors of this paper) then decided to study and formalize Julia and uncovered gems like this (I guess they are gems particularly if you care about formal treatments).

I am certain I am somewhat wrong in this description, but I would love to see a writeup of the whole story and how both sides (the devs and the scientists) lived through it.