I'm actually somewhat intrigued with the idea of using guix[0] as a language package manager. It has really nice facilities for setting up "environments" that contain a set of packages, so you can use it for bundling together all of the deps needed to build a particular application. As a bonus, it uses scheme as its configuration language :)
It wouldn't solve arc side of actually loading packages, which probably still needs work, but it should work pretty well at managing them.