composing method and function

Common.scala

  def array2Pair(a: Array[String]): UserScore = {
    if (a.size != 2) throw new NotArray2

    (a(0).toLong, a(1).toDouble)
  }

  io.Source.fromFile(fileName).getLines().map(_.split("\t")).map(array2Pair(_))

How do we compose split and array2Pair in one call, like (f andThen g)(x) ?