Diagnostic Quiz

Problems

6. How many times will an lambda be evulated in an Infinite List

If you call get(n), the the lambda expression in the itearte() will be ecaluated n times!

Since get(n), and n is 5, the lambda expression will be evaluated 5 times!

8-11. Use Heap Diagram to trace the program

1. When you call infiList1 = InfiniteList.operation, the head and tail fields in the infiList1 point to two anonymous classes implemented in lambdas which capture the variable appeared in that lambda.

2. When you call infiList2 = infiList1.opeartion, the head and tail fields in teh infiList2 point to two anonymouse classes also, but with another this field in each of them, which points to infiList1.

3. Also include the code, the implementation for some InfiniteList operations and pictures from the lecture into the Cheatsheet!

Given this modified version of InfiniteList::map,

public <R> InfiniteList<R> map(Transformer<? super T, ? extends R> mapper, int tag) {
  System.out.print(tag + " ");
  InfiniteList<R> list = new InfiniteList<>(
      () -> mapper.transform(this.head()),
      () -> this.tail().map(mapper, tag + 1));
  System.out.print(tag + " ");
  return list;
}

What will be printed by the code snippet below?

InfiniteList.iterate(0, x -> x + 1)
    .map(x -> x + 1, 7)
    .map(x -> x * 2, 20)
    .get(1);

This question is a bit tedious, but the stack and heap diagram should be easy to draw following the above rules. The answer is 7 7 20 20 8 8 21 21.

13. Infinite Loop in Stream

1. sorted() and distinct() should only be called on finite streams. Otherwise, the program will enter an infinite loop.

Tips

1. When calling get(n) in EagerList or InfiniteList, notice the the index of the element in the list starts from 0!

2. Stack and Heap Diagram for Infinite List Rules of thumb

   1. When you call infiList1 = InfiniteList.operation, the head and tail fields in the infiList1 point to two anonymous classes implemented in lambdas which capture the variable appeared in that lambda.

   2. When you call infiList2 = infiList1.opeartion, the head and tail fields in teh infiList2 point to two anonymouse classes also, but with another this field in each of them, which points to infiList1.

   3. Also include the code, the implementation for some InfiniteList operations and pictures from the lecture into the Cheatsheet!

3. sorted() and distinct() should only be called on finite streams. Otherwise, the program will enter an infinite loop.