// https://docs.scala-lang.org/tour/implicit-parameters.html
abstract class Monoid[A] {
def add(x: A, y: A): A
def unit: A
}
object ImplicitTest {
implicit val stringMonoid: Monoid[String] = new Monoid[String] {
def add(x: String, y: String): String = x concat y
def unit: String = ""
}
implicit val intMonoid: Monoid[Int] = new Monoid[Int] {
def add(x: Int, y: Int): Int = x + y
def unit: Int = 0
}
def sum[A](xs: List[A])(implicit m: Monoid[A]): A =
if (xs.isEmpty) m.unit
else m.add(xs.head, sum(xs.tail))
def main(args: Array[String]): Unit = {
println(sum(List(1, 2, 3))) // uses intMonoid implicitly
println(sum(List("a", "b", "c"))) // uses stringMonoid implicitly
}
}Languages with Implicit Arguments include Scala, Aardvark
View all concepts with or missing a hasImplicitArguments measurement
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