在Scala中使用类型类模式的性能影响是什么？

>许多额外的虚拟方法调用
>可能拳击原语(例如,如果使用scalaz的类型为monoid等)
>通过def进行对象创建,这是必需的,因为函数不能被参数化
>对象创建访问“pimped”方法

在运行时,JVM可以优化某些错误的创建(例如,仅仅创建MA来调用*),但是scalac并没有太多的帮助.您可以通过编译使用类型类和使用-Xprint：icode作为参数的一些代码来看到这一点.

以下是一个例子：

import scalaz._; import Scalaz._
object TC {
  def main(args: Array[String]) {
    println((args(0).parseInt.liftFailNel |@| args(1).parseInt.liftFailNel)(_ |+| _))
  }
}

这里是icode：

final object TC extends java.lang.Object with ScalaObject {
  def main(args: Array[java.lang.String]): Unit = scala.this.Predef.println(scalaz.this.Scalaz.ValidationMA(scalaz.this.Scalaz.StringTo(args.apply(0)).parseInt().liftFailNel()).|@|(scalaz.this.Scalaz.StringTo(args.apply(1)).parseInt().liftFailNel()).apply({
  (new anonymous class TC$$anonfun$main$1(): Function2)
},scalaz.this.Functor.ValidationFunctor(),scalaz.this.Apply.ValidationApply(scalaz.this.Semigroup.NonEmptyListSemigroup())));
def this(): object TC = {
  TC.super.this();
  ()
}
};
@SerialVersionUID(0) final <synthetic> class TC$$anonfun$main$1$$anonfun$apply$mcIII$sp$2 extends scala.runtime.AbstractFunction0 with Serializable {
  final def apply(): Int = TC$$anonfun$main$1$$anonfun$apply$mcIII$sp$2.this.v1$1;
  final <bridge> def apply(): java.lang.Object = scala.Int.box(TC$$anonfun$main$1$$anonfun$apply$mcIII$sp$2.this.apply());
  <synthetic> <paramaccessor> private[this] val v1$1: Int = _;
  def this($outer: anonymous class TC$$anonfun$main$1,v1$1: Int): anonymous class TC$$anonfun$main$1$$anonfun$apply$mcIII$sp$2 = {
    TC$$anonfun$main$1$$anonfun$apply$mcIII$sp$2.this.v1$1 = v1$1;
    TC$$anonfun$main$1$$anonfun$apply$mcIII$sp$2.super.this();
    ()
  }
};
@SerialVersionUID(0) final <synthetic> class TC$$anonfun$main$1$$anonfun$apply$mcIII$sp$1 extends scala.runtime.AbstractFunction0$mcI$sp with Serializable {
  final def apply(): Int = TC$$anonfun$main$1$$anonfun$apply$mcIII$sp$1.this.apply$mcI$sp();
  <specialized> def apply$mcI$sp(): Int = TC$$anonfun$main$1$$anonfun$apply$mcIII$sp$1.this.v2$1;
  final <bridge> def apply(): java.lang.Object = scala.Int.box(TC$$anonfun$main$1$$anonfun$apply$mcIII$sp$1.this.apply());
  <synthetic> <paramaccessor> private[this] val v2$1: Int = _;
  def this($outer: anonymous class TC$$anonfun$main$1,v2$1: Int): anonymous class TC$$anonfun$main$1$$anonfun$apply$mcIII$sp$1 = {
    TC$$anonfun$main$1$$anonfun$apply$mcIII$sp$1.this.v2$1 = v2$1;
   TC$$anonfun$main$1$$anonfun$apply$mcIII$sp$1.super.this();
  ()
  }
};
@SerialVersionUID(0) final <synthetic> class TC$$anonfun$main$1 extends scala.runtime.AbstractFunction2$mcIII$sp with Serializable {
  final def apply(x$1: Int,x$2: Int): Int = TC$$anonfun$main$1.this.apply$mcIII$sp(x$1,x$2);
  <specialized> def apply$mcIII$sp(v1$1: Int,v2$1: Int): Int = scala.Int.unbox(scalaz.this.Scalaz.mkIdentity({
(new anonymous class TC$$anonfun$main$1$$anonfun$apply$mcIII$sp$2(TC$$anonfun$main$1.this,v1$1): Function0)
}).|+|({
    (new anonymous class TC$$anonfun$main$1$$anonfun$apply$mcIII$sp$1(TC$$anonfun$main$1.this,v2$1): Function0)
},scalaz.this.Semigroup.IntSemigroup()));
final <bridge> def apply(v1: java.lang.Object,v2: java.lang.Object): java.lang.Object = scala.Int.box(TC$$anonfun$main$1.this.apply(scala.Int.unbox(v1),scala.Int.unbox(v2)));
  def this(): anonymous class TC$$anonfun$main$1 = {
    TC$$anonfun$main$1.super.this();
    ()
   }
 }

}

您可以看到在这里有大量的对象创建