x = y =1 in Scala?

Question

While going through the book Scala for the Impatient, I came across this question:

Come up with one situation where the assignment x = y = 1 is valid in Scala. (Hint: Pick a suitable type for x.)

I am not sure what exactly the author means by this question. The assignment doesn't return a value, so something like var x = y = 1 should return Unit() as the value of x. Can somebody point out what might I be missing here?

Thanks

Answer 1

In fact, x is Unit in this case:

var y = 2
var x = y = 1

can be read as:

var y = 2
var x = (y = 1)

and finally:

var x: Unit = ()

Answer 2

You can get to the point of being able to type x=y=1 in the REPL shell with no error thus:

var x:Unit = {}
var y = 0
x = y = 1