Non Blocking Channel Operations in Prolog

Our program demonstrates non-blocking channel operations in Prolog. While Prolog doesn’t have built-in channels like Go, we can simulate similar behavior using Prolog’s message passing mechanism.

:- use_module(library(concurrent)).

main :-
    thread_create(message_thread, _, []),
    thread_create(signal_thread, _, []),
    
    % Non-blocking receive
    (   thread_peek_message(message(Msg))
    ->  format('received message ~w~n', [Msg])
    ;   format('no message received~n')
    ),
    
    % Non-blocking send
    Msg = 'hi',
    (   thread_send_message(message(Msg), [timeout(0)])
    ->  format('sent message ~w~n', [Msg])
    ;   format('no message sent~n')
    ),
    
    % Multi-way non-blocking select
    (   thread_peek_message(message(ReceivedMsg))
    ->  format('received message ~w~n', [ReceivedMsg])
    ;   thread_peek_message(signal(Signal))
    ->  format('received signal ~w~n', [Signal])
    ;   format('no activity~n')
    ).

message_thread :-
    true.

signal_thread :-
    true.

In this Prolog version:

1. We use the concurrent library for thread-based concurrency.

2. We create two threads: message_thread and signal_thread, which simulate the channels in the original Go code.

3. For non-blocking receive, we use thread_peek_message/1. If a message is available, it’s processed; otherwise, the program continues.

4. For non-blocking send, we use thread_send_message/2 with a timeout of 0. This attempts to send a message immediately, failing if it can’t be sent right away.

5. For the multi-way non-blocking select, we use a series of thread_peek_message/1 calls in an if-then-else structure to check for different types of messages.

To run the program:

?- main.
no message received
no message sent
no activity

This Prolog implementation provides similar functionality to the original Go code, demonstrating non-blocking operations in a concurrent environment. However, it’s important to note that Prolog’s concurrency model is different from Go’s, and this example is a simplified simulation of the concepts.