Hello.scala

package org.example

import scala.io.Source

object Hello extends App {
  def find_(keyword: String, root: java.io.File): Seq[java.io.File] = {
    import sys.process._
    (s"grep -l -r -s -I '$keyword' $root" lines_!) map {
      new java.io.File(_)
    }
  }

  def find(keyword: String, root: java.io.File): Seq[java.io.File] = {
    def from(files: Seq[java.io.File]): Stream[java.io.File] = {
      val newFiles:Seq[java.io.File] = files.head match {
        case file if file.isFile => files.tail
        case dir if dir.isDirectory => dir.listFiles ++ files.tail
      }
      // FIXME: if ~ else かっこ悪い
      Stream.cons(files.head, if (newFiles.isEmpty) Stream.empty[java.io.File]
        else from(newFiles))
    }

    from(root.listFiles) filter { file =>
      file.isFile && Source.fromFile(file).getLines().exists(_.contains(keyword))
    }
  }

  val file = new java.io.File("/")


  println(find("a", file))
}