CODEWITHSUNDEEP
scalacollectionsscala-2.13
Suma
Suma

Reputation: 34463

How to make a function working with different collection type in Scala 2.13?

Following function accepted more or less any collection and returned it filtered:

def filterEven[Repr](o: collection.IterableLike[Int, Repr]): Repr = {
  o.filter { o =>
    (o % 2) == 0
  }
}

filterEven(List(1, 2, 3))

filterEven(Set(1, 2, 3))

How do I achieve the same with Scala 2.13? IterableLike no longer exists there. Should I use higher kinded types somehow?

Upvotes: 1

Views: 183

Answers (1)

Suma
Suma

Reputation: 34463

It seems higher kinded types together with IterableOps can be used to achieve this:

def filterEven[CC[Int] <: IterableOps[Int, CC, CC[Int]]](o: CC[Int]): CC[Int] = {
  o.filter { o =>
    (o % 2) == 0
  }
}

I found this more logical than the previous Repr based solution.

Inspired by Adding custom collection operations in scala 2.13 to arbitrary collections of specific types

Upvotes: 3

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