FrequencyAnalysis.scala

import scala.io.Source._

try
{
	val datas =	fromFile( args(0) ).mkString	// file's text to a BIG string
		.groupBy( x => x )		// group occurrences into strings in a map (Char -> String)
		.mapValues( _.size )		// converts map (Char -> Int) => where Int is: String.size
		.toList				// map to list (preparing it for sorting)
		.sortWith( _._2 > _._2 )	// reverse sorting with the 2nd value of each element

	datas.foreach {
		v => println(
			"'" + v._1 + "' -> " + v._2			// char -> occurrences number
			+ "  (" + v._2.toFloat * datas.size / 100 + ")"	// (ratio)
		)
	}
}
catch
{
	case a:java.lang.ArrayIndexOutOfBoundsException	=> println( "No arg given" )
	case f:java.io.FileNotFoundException		=> println( "File not found" )
}

Scala is kind of a coffee maker !