Range Over Channels in Racket

Our example demonstrates how to iterate over values received from a channel in Racket. While Racket doesn’t have built-in channels like Go, we can simulate this behavior using a queue data structure and threads.

#lang racket

(require data/queue)

(define (main)
  ; We'll iterate over 2 values in the 'queue' channel.
  (define queue (make-queue))
  (enqueue! queue "one")
  (enqueue! queue "two")
  
  ; This loop iterates over each element as it's
  ; received from 'queue'. We'll use a separate
  ; thread to simulate channel behavior.
  (thread
   (λ ()
     (let loop ()
       (unless (queue-empty? queue)
         (displayln (dequeue! queue))
         (loop)))))
  
  ; Wait a bit to allow the thread to finish
  (sleep 1))

(main)

To run the program:

$ racket range-over-channels.rkt
one
two

This example shows how we can simulate channel-like behavior in Racket using a queue and threads. While Racket doesn’t have built-in channels, this approach allows us to achieve similar functionality.

In this implementation, we use a queue to store the values and a separate thread to process them. The main thread adds values to the queue and starts a new thread that dequeues and prints the values. The sleep at the end ensures the program doesn’t exit before the processing thread finishes.

Note that unlike in the original example where closing the channel terminates the iteration, in this Racket version, we simply continue until the queue is empty. For more complex scenarios, you might need to implement additional signaling mechanisms to indicate when processing should stop.