I just came across a blog post by Sönke who is the author of vibe.d and a long time D user. He wrote:
>Aspect is rather unusual with regard to the programming language that is used for building it. Not only the application itself, but also most of the underlying libraries are written in the D programming language. This choice has led to productivity boosts and design decisions without which Aspect probably wouldn't be here today...
Read more here: https://aspect.bildhuus.com/blog/posts/how-we-are-using-d-from-the-ground-up