CODEWITHSUNDEEP
scalagenericspartialfunction
Bruno
Bruno

Reputation: 250

Scala : Collect with generics

Given the following scenario

val items = List("a", "b", "c", 1, 2, 3, false, true)
def intItems = items.collect {case i : Int => i}
def stringItems = items.collect {case s : String => s}

is there a way to create a generic function to handle this behavior?

I tried the following

def itemsAs[T]: List[T] = items.collect { case item: T => item }

but

itemsAs[Int]

returns

List[Int]] = List(a, b, c, 1, 2, 3, false, true)

Another approach is to provide the partial function as argument, but still have to duplicate the case i: Int => i and case s: String => s. Is there a way to make it more compact? Thanks

Upvotes: 3

Views: 297

Answers (1)

dveim
dveim

Reputation: 3482

val items = List("a", "b", "c", 1, 2, 3, false, true)
import scala.reflect.ClassTag
def collect[T: ClassTag] = items.collect { case x: T => x }
collect[Int] // List(1, 2, 3)
collect[String] // List(a, b, c)

See http://docs.scala-lang.org/overviews/reflection/typetags-manifests.html for more details.

Upvotes: 5

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