Question

I know you can create an anonymous function, and have the compiler infer its return type:

val x = () => { System.currentTimeMillis }

Just for static typing’s sake, is it possible to specify its return type as well? I think it would make things a lot clearer.

Answer 1

In my opinion if you’re trying to make things more clear it is better to document the expectation on the identifier x by adding a type annotation there rather than the result of the function.

val x: () => Long = () => System.currentTimeMillis

Then the compiler will ensure that the function on the right hand side meets that expectation.