Scala.jsでパターンマッチがどのように変換されるか

Scala.jsでパターンマッチの変換結果 2013 7.24現在.js

  ScalaJS.c.helloworld\ufe33HelloWorld$.prototype.hoge\ufe34O\ufe34V = (function(arg$num) {
    var rc6$jsid$17007 = false;
    var x2$jsid$17002 = null;
    var x1$jsid$17001 = arg$num;
    var result$$jslabel$matchEnd7$17008;
    // Someはそのままの機能、if文を並べつつ代入＆ラベルでbreak(このbreakの機能初めて知った)
    $jslabel$matchEnd7$17008: {
      if (ScalaJS.is.scala\ufe33Some(x1$jsid$17001)) {
        rc6$jsid$17007 = true;
        x2$jsid$17002 = ScalaJS.as.scala\ufe33Some(x1$jsid$17001);
        var hoge$jsid$12146 = x2$jsid$17002.x\ufe34O();
        if (ScalaJS.anyEqEq(hoge$jsid$12146, ScalaJS.bI(20))) {
          result$$jslabel$matchEnd7$17008 = ScalaJS.bI(30);
          break $jslabel$matchEnd7$17008
        } else {
          /*<skip>*/
        }
      } else {
        /*<skip>*/
      };
      if (rc6$jsid$17007) {
        result$$jslabel$matchEnd7$17008 = ScalaJS.bI(10);
        break $jslabel$matchEnd7$17008
      } else {
        /*<skip>*/
      };
      if (ScalaJS.anyRefEqEq(ScalaJS.modules.scala\ufe33None(), x1$jsid$17001)) {
        result$$jslabel$matchEnd7$17008 = "40";
        break $jslabel$matchEnd7$17008
      } else {
        /*<skip>*/
      };
      // 到達しなかったら例外が飛ぶ
      throw new ScalaJS.c.scala\ufe33MatchError().init\ufe33\ufe34O(x1$jsid$17001);
      break $jslabel$matchEnd7$17008
    };
    var value$jsid$11972 = result$$jslabel$matchEnd7$17008
  });

Scala.jsでパターンマッチの変換結果 2014 3.29現在.js

// 昔と比べて無駄なelse文がなくなった
ScalaJS.c.HelloWorld$.prototype.hoge__O__V = (function(num) {
  var rc6 = false;
  var x2 = null;
  var x1 = num;
  // Someはそのままの機能、if文を並べつつ代入＆ラベルでbreak
  matchEnd7: {
    if (ScalaJS.is.scala_Some(x1)) {
      rc6 = true;
      x2 = ScalaJS.as.scala_Some(x1);
      var hoge = x2.x__O();
      if (ScalaJS.anyEqEq(hoge, ScalaJS.bI(20))) {
        var value = ScalaJS.bI(30);
        break matchEnd7
      }
    };
    if (rc6) {
      var value = ScalaJS.bI(10);
      break matchEnd7
    };
    if (ScalaJS.anyRefEqEq(ScalaJS.modules.scala_None(), x1)) {
      var value = "40";
      break matchEnd7
    };
    // 到達しなかったら例外が飛ぶ
    throw new ScalaJS.c.scala_MatchError().init___O(x1)
  }
});

元ファイル.scala

object HelloWorld {
  def hoge(num: Any) = {
    var value = num match {
      case Some(hoge) if (hoge == 20) => 30
      case Some(hoge) => 10
      case None => "40"
    }
  }
}