modUp.scala

def modUp[A](a: A, b: A)(implicit num: Integral[A]): A = {
  import num._
  val am = a - one
  val z = if (gteq(am, zero)) am % b else {
    val c = -am % b
    if (c == zero) zero else b - c
  }
  z + one
}

Seq.tabulate(10)(i => modUp(i, 4)) // List(4, 1, 2, 3, 4, 1, 2, 3, 4, 1)