It's been raised many times before. By me and numerous others. The standard library is generic, which isn't the end of the world, but you can't tell from the documentation how you can work with the output. It's common for someone to ask a question and be told "add .array to the output". They'd never know that after reading the documentation.

Reading the example code in the documentation is very helpful with this.

And the "Returns:" section!

I had this issue last year when I started learning D. I eventually got used to it, but it was a stumbling block at first. The #d IRC channel helped me out.