Void

The void type is an empty type. It exists for the cases where a type name is required, but there’s no value for it. For example:

fn some_function() -> ! { ... }

void! val = some_function()
val catch err {
  throw err
}

In this case, some_function does not return a value but can throw an error. In order to assign it to val, it needs to have a type representing the error union, which is where the void type comes in. This is especially useful in the case of async functions:

fut void! val = async some_function()
await val catch err {
  throw err
}

You can also use void as a normal type elsewhere, though it should generally be avoided unless necessary.