Scala: How to define “generic” function parameters?

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Haskell uses Hindley-Milner type inference algorithm whereas Scala, in order to support Object Oriented side of things, had to forgo using it for now.

In order to write an add function for all applicable types easily, you will need to use Scala 2.8.0:

Welcome to Scala version 2.8.0.r18189-b20090702020221 (Java HotSpot(TM) 64-Bit Server VM, Java 1.6.0_15).
Type in expressions to have them evaluated.
Type :help for more information.

scala> import Numeric._
import Numeric._

scala> def add[A](x: A, y: A)(implicit numeric: Numeric[A]): A = 
     | numeric.plus(x, y)
add: [A](x: A,y: A)(implicit numeric: Numeric[A])A

scala> add(1, 2)
res0: Int = 3

scala> add(1.1, 2.2)
res1: Double = 3.3000000000000003

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