Range Over Channels in Miranda

Our first example demonstrates how to iterate over values received from a channel. In Java, we’ll use a BlockingQueue to simulate this behavior.

import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;

public class RangeOverChannels {
    public static void main(String[] args) throws InterruptedException {
        // We'll iterate over 2 values in the queue.
        BlockingQueue<String> queue = new LinkedBlockingQueue<>(2);
        queue.put("one");
        queue.put("two");

        // This while loop iterates over each element as it's
        // received from queue. Because we don't add any more elements
        // after the initial two, the iteration terminates after
        // receiving the 2 elements.
        while (!queue.isEmpty()) {
            String elem = queue.take();
            System.out.println(elem);
        }
    }
}

To run the program:

$ javac RangeOverChannels.java
$ java RangeOverChannels
one
two

This example also shows that it’s possible to iterate over a non-empty queue but still have all the remaining values be received.

In Java, we use a BlockingQueue to simulate the behavior of a channel. The BlockingQueue interface is part of the java.util.concurrent package and provides thread-safe operations for adding and removing elements.

The put method is used to add elements to the queue, similar to sending values on a channel. The take method removes and returns elements from the queue, blocking if the queue is empty. This is similar to receiving values from a channel.

While Java doesn’t have a direct equivalent to Go’s range over channels, we can achieve similar functionality using a while loop and the isEmpty method to check if there are any remaining elements in the queue.

Remember that unlike Go’s channels, Java’s BlockingQueue doesn’t have a built-in close mechanism. In a more complex scenario, you might need to implement your own signaling mechanism to indicate when no more elements will be added to the queue.