コップ本第2版のP.76のプログラムを少しいじったもの

scala_3_6.scala

import scala.io.Source

def widthOfLength(s: String): Int = s.length.toString.length

if (args.length == 0) {
  Console.err.println("Please enter filename")
  sys.exit(-1)
}

val lines = Source.fromFile(args(0)).getLines().toList
val maxWidth = lines.map(widthOfLength).max
val output = lines.map {line =>
  val padding = " " * (maxWidth - widthOfLength(line))
  padding + line.length + " | " + line
}
println(output.mkString("\n"))