Scala Scala REPL 中的数组函数

Question

I tried to create an array in scala.

In scala repl when i put dot and press tab i could see only few function available.

scala> val d = Array(1,2,3,4,5)
d: Array[Int] = Array(1, 2, 3, 4, 5)
scala> d.
apply          asInstanceOf   clone          isInstanceOf   length         toString       update

But i was able to run sum, head,tail etc on Array although scala repl didn't show them.

I couldn't understand why functions such as head, tail etc were not shown by scala repl.

Answer 1

Because Array doesn't actually have those methods. They are defined on either ArrayOps or ArraySeq . There are implicit conversions that allow you invoke those methods directly as if they were defined on array, but what really goes on when you do array.sum is something like ArraySeq.make(array).sum