Scala - Cleaner way of writing generic numeric operation method

Question

Is there a cleaner way of writing this method? Preferably, I wouldn't need to match against all valid Types and instead permit every Type that has the * method. Also, is there a way to not require asInstanceOf[T] at the end?

def expr_neg[T <: AnyVal](value: T): T = value match { case int: Int => (int * -1).asInstanceOf[T] case long: Long => (long * -1).asInstanceOf[T] case float: Float => (float * -1).asInstanceOf[T] case double: Double => (double * -1).asInstanceOf[T] }

If you are interested in numerical computations using scala, you should check out github.com/non/spire. It contains a much richer set of typeclasses than just numeric. — Rüdiger Klaehn
– Rüdiger Klaehn, Commented Jul 11, 2015 at 16:16

melps · Accepted Answer · 2015-07-10 16:54:51Z

You would be much better off using the Numeric Typeclass:

 def exprNeg[T:Numeric](value: T): T = { val n = implicitly[Numeric[T]] n.negate(value) }

Lukas Wegmann · Accepted Answer · 2015-07-10 20:51:07Z

In addition to @melps answer, it is also possible to use the arithmetic operators provided by Numeric.Implicits:

import Numeric.Implicits._ def f[T: Numeric](x: T) = -x

Which is pretty cool, but unfortunately never mentioned in the Scala docs. This also works for Ordering:

import Ordering.Implicits._ def g[T: Ordering](x: T) = x < x

Collectives™ on Stack Overflow

Scala - Cleaner way of writing generic numeric operation method

2 Answers 2

Comments

Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Linked

Related