Question

I’m learning Scala now, and I have a scenario where I have to compare an element (say num) with all the elements in a list.

Assume,

val MyList = List(1, 2, 3, 4)

If num is equal to anyone the elements in the list, I need to return true. I know to do it recursively using the head and tail functions, but is there a simpler way to it (I think I’ll be able to do it using foreach, but I’m not sure how to implement it exactly)?

Answer 1

There is number of possibilities:

val x = 3
MyList.contains(x)
!MyList.forall(y => y != x) // early exit, basically the same as .contains

If you plan to do it frequently, you may consider to convert your list to Set, cause every .contains lookup on list in worst case is proportional to number of elements, whereas on Set it is effectively constant

val mySet = MyList.toSet
mySet.contains(x)

or simply:

mySet(x)