我正在阅读M. Odersky的
Scala编程,他说
Functions like approximate,which call themselves as their last
action,are called tail recursive.
所以,我试过这个:
object Main extends App { implicit val mc = new MyClass(8) val ti = new TestImplct ti.test } class TestImplct { def test(implicit mc : MyClass): Unit = { println(mc.i) mc.i -= 1 if(mc.i < 0){ throw new IllegalArgumentException } test } } class MyClass(var i : Int)
但它会生成以下堆栈跟踪
Exception in thread "main" java.lang.IllegalArgumentException at TestImplct.test(Main.scala:13) at TestImplct.test(Main.scala:15) at TestImplct.test(Main.scala:15) at TestImplct.test(Main.scala:15) at TestImplct.test(Main.scala:15) at TestImplct.test(Main.scala:15) at TestImplct.test(Main.scala:15) at TestImplct.test(Main.scala:15) at TestImplct.test(Main.scala:15)
这意味着它为每个递归调用生成一个新的堆栈帧.但最后一步是呼唤自己.什么是错的,如何让它尾递归?
为什么编译器不进行尾调用优化?