Scala - Core Scala - More Collections(Fibonacci series, List, Buffer)

Learning Scala:
Practical Functional Programming for the JVM
(O'Reilly Media)
Jason Swartz (著)

開発環境

• OS X El Capitan - Apple (OS)
• Emacs (Text Editor)
• Scala (プログラミング言語)

Learning Scala: Practical Functional Programming for the JVM (Jason Swartz (著)、O'Reilly Media)のPart Ⅰ. (Core Scala)、Chapter 7.(More Collections)、Exercises 1-a.(No. 3180)を解いてみる。

その他参考書籍

• Programming Scala: Scalability = Functional Programming + Objects

Exercises 1-a.(No. 3180)

コード(Emacs)

def fibonacci(x : Int): List[Int] = {
  x match {
    case 0  => List(0)
    case 1 => List(0, 1)
    case _ => {
      val buffer = List(0, 1).toBuffer
      while (buffer.size < x) buffer += buffer.takeRight(2).sum
      buffer.toList
    }
  }
}

for (x <- List(0, 1, 2, 3, 4, 10)) {
  println(fibonacci(x))
}

入出力結果(Terminal, REPL(Read, Eval, Print, Loop))

$ scala-2.11 sample1_a.scala
List(0)
List(0, 1)
List(0, 1)
List(0, 1, 1)
List(0, 1, 1, 2)
List(0, 1, 1, 2, 3, 5, 8, 13, 21, 34)
$