gistfile1.scala

import java.io.InputStream
import java.io.FileInputStream

object Main {
    implicit def streamToPimpedStream(stream: InputStream) = new PimpedInputStream(stream)

    def main(args: Array[String]) {
      def master = new FileInputStream("C:\\test1.txt")
      val identical = new FileInputStream("C:\\test2.txt")
      val modified = new FileInputStream("C:\\test3.txt")

      println(master.isIdentical(identical) == true)   
      println(master.isIdentical(modified) == false)   
    }
}

class PimpedInputStream(stream: InputStream) {
  val READ_SIZE = 65535

  def isIdentical(other: InputStream): Boolean = {
    isIdenticalRecursive(stream, other)
  }

  private def isIdenticalRecursive(left: InputStream, right: InputStream): Boolean = {
      val ourBytes = Array.ofDim[Byte](READ_SIZE)
      val theirBytes = Array.ofDim[Byte](READ_SIZE)  
      val bytesRead = List(left.read(ourBytes), right.read(theirBytes))

      //Both streams have been fully read
      if(bytesRead.forall(_ == -1)) 
        true
      else if(!ourBytes.sameElements(theirBytes))
        false
      else 
        isIdenticalRecursive(left, right)
  }
}