Mercurial was written entirely in Python for quite a while.
But more to the point, I doubt there are many ideas for which the choice of implementation language is core to the idea. Maybe that's how it was presented, but that's usually because you need a concrete realization of an idea in order for people to even get what you're talking about.
But more to the point, I doubt there are many ideas for which the choice of implementation language is core to the idea. Maybe that's how it was presented, but that's usually because you need a concrete realization of an idea in order for people to even get what you're talking about.