How to Write Generic Numeric Function in Scala?

Question

I know this question may be answered a lot of times, however I cannot find a post that can solve my question. My question is I want to write a generic function that can take Int, Double or BigDecimal and do the calculation.

def foo[T: Numeric](returns: Seq[T])(implicit ev: T => Ordered[T]): Seq[T]= {
    returns.filter(_ >= 0)
}

However I got a Type Match error, because 0 is a Int. If there any way that can make it work for any Numeric type.

Luis Miguel Mejía Suárez · Accepted Answer · 2019-09-05 21:13:42Z

1

Try this.

def foo[T](returns: Seq[T])(implicit N: Numeric[T]): Seq[T] = {
  import N._
  returns.filter(_ >= N.zero)
}

The scaladoc is your friend.

answered Sep 5, 2019 at 21:13

Luis Miguel Mejía Suárez

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Comments

Seth Tisue · Accepted Answer · 2019-09-05 22:59:17Z

1

Would rather ...

def foo[T](returns: Seq[T])(implicit n: Numeric[T]): Seq[T] =
  returns.filter { v => n.compare(v, n.zero) >= 0 }

edited Sep 5, 2019 at 22:59

Seth Tisue

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answered Sep 5, 2019 at 21:19

cchantep

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