Quote o' the day: Mmmm, pudding
Maristic, answering the question, "Why is the D compiler not implemented in D? Wouldn't that be the proof of the pudding?":
No, at least not the way you've phrased it. It seems like you're basing your notion on the phrase the proof is in the pudding, possibly imagining that it requires a kind of recursive pudding bootstrap where puddings contain their own proof.
But the full version of the phrase is actually the proof of the pudding is in the eating. In other words, it's most important how well other people do in eating the delicious pudding that D is rather than how much its author enjoys D pudding.
Thus opening up the new and exciting field of dependently typed desserts.