Replace element in List with scala

Question

How do you replace an element by index with an immutable List.

E.g.

val list = 1 :: 2 ::3 :: 4 :: List()

list.replace(2, 5)

Answer 1

In addition to what has been said before, you can use patch function that replaces sub-sequences of a sequence:

scala> val list = List(1, 2, 3, 4)
list: List[Int] = List(1, 2, 3, 4)

scala> list.patch(2, Seq(5), 1) // replaces one element of the initial sequence
res0: List[Int] = List(1, 2, 5, 4)

scala> list.patch(2, Seq(5), 2) // replaces two elements of the initial sequence
res1: List[Int] = List(1, 2, 5)

scala> list.patch(2, Seq(5), 0) // adds a new element
res2: List[Int] = List(1, 2, 5, 3, 4)