CODEWITHSUNDEEP
javascala
Ahmed El-Salamony
Ahmed El-Salamony

Reputation: 11

Scala overloading Methods

I have a little question about this piece of code (which does not compile) :

       def avg(seq: Seq[Int]): Double = seq.sum.toDouble/seq.length
       def avg(seq: Seq[Double]): Double = seq.sum/seq.length

the idea is simple as shown above, the first method calculates the average to a sequence of integers, and the second does the same to a seq of Doubles

but it gives me a compilation error around repetition, I want to know why...and if you have a much Scala approach than this code to perform the same idea please, share it in your answer Thank you

Upvotes: 0

Views: 74

Answers (1)

jwvh
jwvh

Reputation: 51271

The problem is due to type erasure, which can be overcome by using the Numeric type class.

def avg[N:Numeric](ns :Seq[N]) :Double =
  implicitly[Numeric[N]].toDouble(ns.sum) / ns.length

avg(List(3, 5, 7, 11))           //res0: Double = 6.5
avg(Vector(9.2, 3.3, 1.7, 21.1)) //res1: Double = 8.825

You can also place it in an implicit class for a more concise expression.

implicit class GetAvg[N:Numeric](ns :Seq[N]) {
  def avg :Double = implicitly[Numeric[N]].toDouble(ns.sum) / ns.length
}

Stream(3, 5, 7, 11).avg      //res2: Double = 6.5
Seq(9.2, 3.3, 1.7, 21.1).avg //res3: Double = 8.825

Upvotes: 3

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