Incomptable Type

Question

I don't know what the error is , and where is Boolean exist in this code . Anybody can solve this error
https://code.sololearn.com/c9nT93RoSHJY/?ref=app

Answer 1

I think you are using the when in a wrong way, if i check with the sololearn lessons, it should look more like this:
val result = when {
size==1 -> msg+list.first()
size>=2 -> msg+list.joinToString("and")
else -> msg+list.subList(0,size-2).joinToString(",")+"and "+list.last()
}
return result
and the second condition should be size>=2

Answer 2

The when(size) should be when.

Answer 3

It works:
https://code.sololearn.com/c57HbXzUCtM2/?ref=app