Как в Scala обобщить Int и BigInt?

import Integral.Implicits._

object Main {
 
  def half[T:Integral](a:T) : T = a / 2.asInstanceOf[T]
  def odd[T:Integral](a:T) : Boolean = a % 2.asInstanceOf[T] == 1.asInstanceOf[T]
  
  def mult_acc11[T:Integral](n:T, a:T, r:T = 0) : T = (odd(n), n) match {
    case (true, 1) => r + a
    case (true, _) => mult_acc11(half(n), a + a, r + a)
    case (_,_)     => mult_acc11(half(n), a + a, r)
  }
  
  def main(args: Array[String]): Unit = {
    def f(n: Int) = (BigInt(1) to BigInt(n)).product
    println(mult_acc11(7,5))
  }
}