Scala - Core Scala - More Collections(Fibonacci series, Stream collection)

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-c.(No. 3195)を解いてみる。

その他参考書籍

• Programming Scala: Scalability = Functional Programming + Objects

Exercises 1-c.(No. 3195)

コード(Emacs)

def fibonacci_stream(i1: Int, i2: Int): Stream[Int] = {
  i1 #:: fibonacci_stream(i2, i1 + i2)
}

val fibonacci_series = fibonacci_stream(0, 1)
val fibonacci_list = fibonacci_series.take(100)

var i = 0
for (n <- fibonacci_list) {
  print(s"$n ")
  i += 1
  if (i % 10 == 0) println()
}

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

$ scala-2.11 sample1_c.scala
0 1 1 2 3 5 8 13 21 34 
55 89 144 233 377 610 987 1597 2584 4181 
6765 10946 17711 28657 46368 75025 121393 196418 317811 514229 
832040 1346269 2178309 3524578 5702887 9227465 14930352 24157817 39088169 63245986 
102334155 165580141 267914296 433494437 701408733 1134903170 1836311903 -1323752223 512559680 -811192543 
-298632863 -1109825406 -1408458269 1776683621 368225352 2144908973 -1781832971 363076002 -1418756969 -1055680967 
1820529360 764848393 -1709589543 -944741150 1640636603 695895453 -1958435240 -1262539787 1073992269 -188547518 
885444751 696897233 1582341984 -2015728079 -433386095 1845853122 1412467027 -1036647147 375819880 -660827267 
-285007387 -945834654 -1230842041 2118290601 887448560 -1289228135 -401779575 -1691007710 -2092787285 511172301 
-1581614984 -1070442683 1642909629 572466946 -2079590721 -1507123775 708252800 -798870975 -90618175 -889489150
$