http://cppquiz.org/ is a brilliant idea. Have a look! (*)
I used it when I was learning C++.
The problem it is combating is that it’s very hard to learn things by RTFM. You need to be pretty high on the Autism Spectrum to be able to assimilate C++ from the spec (“I know Kung Fu”… Neo). For the rest of us it’s a case of active repetition in order to reinforce learning – you need to be active for the learning to take place. You need to try something out and get a result and you wlil naturally learn from the experience. I remember learning French vocab at school by writing words in one column and the translation in a second column and covering one column with a piece of paper which I would move down one word at the time to stimulate recall. Horrible memory, but it worked!
If you read the small print on that site, the actual engine is available on GitHub (https://github.com/knatten/cppquiz). It may be practical to clone it and fill it up with Julia questions and have JuliaQuiz.org. And then anyone who thinks up a neat question could just muck in on GitHub.
I don’t mind doing it, although it might be better if some official Julia person registered juliaquiz.org.
However I’m not sure Julia would get as much benefit a C++. C++ contains a zillion vexing edge cases and a lot of unintuitive behaviour – most of the questions on that site have surprising answers. Modern languages have attempted to reduce the amount of surprise.
What think ye?
(*) Note: If you make three attempts at an answer it lets you view the solution, which contains a full explanation including relevant parts of the spec.