D had such a great chance to become one of the big languages, but it really royally screwed things up for a long time there with the two different and incompatible standard libraries and the optional GC that was less than optional most of the time, especially depending on which standard library you picked, and thus locked yourself out of a portion of the library ecosystem).

Nowadays it’s more settled down, one standard library basically took over, still has the optional(ish) GC, but it’s basically too late at this point. However, the language has some really cool aspects of its design, and it’s well worth learning just to see those things, things that some of this idioms show off too.