CODEWITHSUNDEEP
scalatuples
lolveley
lolveley

Reputation: 1719

apply used with a tuple does not work

I tried to use "spire", a math framework for scala, but I have an unexpected error.Here is my little program:

import spire.algebra._
import spire.implicits._

trait AbGroup[A] extends Group[A]

final class Rationnel_Quadratique(val n1: Int = 2)(val coef: (Int, Int)) {
override def toString = {
    coef match {
        case (c, i) =>
            s"$c + $i√$n"
    }
}

def a() = coef._1

def b() = coef._2

def n() = n1


}

object Rationnel_Quadratique {

def apply(coef: (Int, Int),n: Int = 2) {
    new Rationnel_Quadratique(n)(coef)
}


}

object AbGroup {

implicit object RQAbGroup extends AbGroup[Rationnel_Quadratique] {
    def +(a: Rationnel_Quadratique, b: Rationnel_Quadratique): Rationnel_Quadratique = Rationnel_Quadratique(coef=(a.a() + b.a(), a.b() + b.b()))   <---

    def inverse(a: Rationnel_Quadratique): Rationnel_Quadratique = Rationnel_Quadratique((-a.a(), -a.b()))

    def id: Int = Rationnel_Quadratique((0, 0))
}

}


object euler66_2 extends App {

println("salut")

val a = r"10/7"
val b = r"5/12"
println(a / b)

val c = Rationnel_Quadratique(1, 2)
val d = Rationnel_Quadratique(3, 4)
val e = c + d
println(e)


}

the error relies not on maths but on the apply method : in the line with the arrow the compiler does not allow the use of tuple :

type mismatch; found : Unit required: Rationnel_Quadratique def +(a: Rationnel_Quadratique, b: Rationnel_Quadratique): Rationnel_Quadratique = Rationnel_Quadratique(coef= ^

I would rather not use maps.can you help me?

Upvotes: 1

Views: 99

Answers (1)

cmbaxter
cmbaxter

Reputation: 35463

You have defined the apply method on the Rationnel_Quadratique companion to return Unit. Change the apply definition to:

def apply(coef: (Int, Int),n: Int = 2) = {
  new Rationnel_Quadratique(n)(coef)
}

Adding the = sign will make sure the apply method has a return type.

Upvotes: 1

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