gistfile1.scala

package forcomp

import common._

object Phonenumber {
  val dictionary = loadDictionary
  val keyMap = Map(
      '2' -> "ABC", '3' -> "DEF", '4' -> "GHI", '5' -> "JKL",
      '6' -> "MNO", '7' -> "PQRS", '8' -> "TUV", '9' -> "WXYZ"
  )
  val letterMap = for ((num, letters) <- keyMap; letter <- letters) yield (letter -> num)
  
  def wordToNumber(word: String): String =
    word.toUpperCase.map(letterMap)
 
  lazy val keypadDictionary =
    dictionary
      .filter(w => w.forall(_.isLetter))
      .groupBy(wordToNumber) 
      .withDefaultValue(List())
  
  def anagrams(number: String): List[List[String]] =
    if (number.isEmpty) List(List())
    else
      (for {
        n <- (1 to number.length)
        word <- keypadDictionary(number.take(n))
        rest <- anagrams(number.drop(n))
      } yield word :: rest).toList
        
  def main(args: Array[String]) =
    anagrams("7225247386") map (_.mkString(" ")) foreach println
    
    //Output:
    //> pack ah re to
    //| pack air fun
    //| pack bird to
    //| rack ah re to
    //| rack air fun
    //| rack bird to
    //| sack ah re to
    //| sack air fun
    //| sack bird to
    //| Scala is fun
    //| Scala ire to
}