Binary to Text (ASCII) Conversion

object Kata {
    def binaryToString(input: String): String = {
    @scala.annotation.tailrec
    def toNumber(st: String, two: Int = 128, number: Int = 0): Int =
      if (st.isEmpty) number
      else toNumber(st.tail, two / 2, st.head.asDigit * two + number)

    input.grouped(8).map[Char](s => toNumber(s).toChar).mkString
  }
}