It's not only not really idiomatic, it's almost never necessary in practice. I was struggling to think of a time I'd ever given a type annotation to an integer

It's not only not really idiomatic, it's almost never necessary in practice. I was struggling to think of a time I'd ever given a type annotation to an integer local variable - because normally the place the variable ends up dictates the type. Local variable becomes part of struct? Struct dictates type. Passed into function? Function dictates type. Multiplied by other variable and then that is passed to function? The type is determined by the function.