Primecoin is an altcoin which uses prime-searching as its proof-of-work.
It is the first energy-multiuse altcoin - normally, the proof-of-work algorithms
in altcoins are useful only for the coin itself, but the Primecoin algorithm
is very useful to mathematical research..
Here, I present a new level of hierarchy on Nixpkgs: the Altcoins.
The idea is to put a single cryptocurrency per file, and build them
using expressions like altcoins.bitcoin. I believe this ordering is
clearer and more maintainable that the current one.