> What's worse, unlike JavaScript which only has two colors (async and non-async), Java has an infinite number colors!

Your comment is great, but I need to point out that the above sentence is misrepresenting Java. You can call any function from a Java function. The fact that you may need to handle an Exception when calling some doesn't make it a "colored" function because you can easily handle the Exception and forget about the color, and if you remember the color problem, it was problematic that colors are infectious, i.e. you just can't get rid of the color, which is not the case in Java. Some claim that's actually bad because it prevents things like structured concurrency (because Java can start a Thread anywhere and there's no way for you to know that a function won't... if there was a "color", or better said, effect, for starting a Thread, you could guarantee that no Thread would be started by a function lacking that effect).