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ScalaNativeにフィボナッチ解かせてみた

Last updated at Posted at 2017-03-15

祝・ScalaNative0.1リリース、ということでフィボナッチを解かせてみた。

http://qiita.com/akira_/items/55cf1f5911b14e265c6f
これのJSコードを移植。

object Main {
  def main(args: Array[String]): Unit = {
    println("Scala Native")
    println(s"fibonacci(46) = ${fibonacci(46)}")
  }
  def fibonacci(n: Long): Long = {
    if (n <= 1) {
      1
    } else {
      fibonacci(n - 1) + fibonacci(n - 2)
    }
  }
}

System.currentTimeMillis()は使えなかった、のでtimeコマンドで計測してみた

環境は↓

CPU:       Quad core Intel Core i7-4870HQ (-HT-MCP-) cache: 6144 KB 
           clock speeds: max: 3700 MHz 1: 3247 MHz 2: 3234 MHz 3: 3268 MHz 4: 3214 MHz 5: 3224 MHz 6: 3251 MHz
           7: 3226 MHz 8: 3270 MHz

そして結果↓

 % time ./target/scala-2.11/scala-native-example-out
Scala Native
fibonacci(46) = 2971215073
./target/scala-2.11/scala-native-example-out  6.48s user 0.00s system 99% cpu 6.480 total

はい

-----追記
上記の結果はビルドオプション( http://www.scala-native.org/en/latest/user/sbt.html#sbt-settings )である nativeMode release のもの。
debug だとかなり遅い。デフォルトだと debug モード。
( sbt "set nativeMode := \"release\"" nativeLink とかで切り替えられる。)

debug モードでの結果↓

 % time ./target/scala-2.11/scala-native-example-out
Scala Native
fibonacci(46) = 2971215073
./target/scala-2.11/scala-native-example-out  14.77s user 0.00s system 99% cpu 14.774 total
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