Everything in Rust has a type. Even functions that don't seem to return anything. In such and similar cases, we're dealing with a Unit Type. Learn about it in this lesson.
This is the same as
void in other languages? Interesting that it uses the tuple syntax.
Yes, I'd say it is comparable to
void in other languages.
The main difference being however that
() is also a value (of type
void has no value.
This StackOverflow answer explains it nicely:
If you're coming from a C-like language (C, C++, Java, etc.), you can think of unit as being like void. It is the type you return when you don't want to return anything. Type theorists will point out that unit is not like void, because unit has exactly 1 value whereas void has 0 values. In practice, the amount of information you can store in both types is the same (0 bits), although languages that use unit tend to be nicer to work with because you can treat it as you would any other value. You can store it in a variable, struct, collection, or anywhere else you could store a value. You can pass as an argument or return it as a result. You can create a reference to it. Etc.