Clay[1] doesn't get as much attention as it deserves. The authors seem well-versed in programming language theory, but they also understand the practical needs of a systems language. What you end up with is a language that's sufficiently low-level to be a C replacement, but it offers a plethora of mechanisms for abstraction.

Of all the new languages billed as "systems languages", Clay is the only one that excites me.

It can also "quack like a duck" (to put it in TFA terms).

[1] http://claylabs.com/clay/