Hello everyone, the compiler forced me to add an else branch in the following snippet. What's the re...

# announcements

[Philipp Mayer]

Hello everyone,
the compiler forced me to add an else branch in the following snippet. What's the reason behind that?

return when ((1..2).random()) {
            1 -> "ABC"
            2 -> "XYZ"
            else -> "???"
        }

The range only includes 1 and 2 and random returns an int.. 🤔

[diesieben07]

random() returns an Int, as such as far as the compiler is concerned it could be any Int.
Even more, 1..2 is just an Int range, it has no information about the size of that range.

[jw]

try return when(1) { 1 -> "" } as well for a more illustrative example. type ranges are not currently refined given compile-time information.

[Ruckus]

Related: https://twitter.com/TimSweeneyEpic/status/1307778368562171904?s=19