Beyond structured concurrency about missionary HOT 5 CLOSED

Released in b.31

from missionary.

1. How is m/replay different from m/stream and m/signal
2. Can you provide a continuous time example under the proposed syntax?

from missionary.

How is m/replay different from m/stream and m/signal

signal is continuous, memoizes the latest value and discards previous ones.
stream is discrete, memoizes each event for a single propagation frame and discards the past
replay is discrete, memoizes all events from start and replays the entire past to new subscribers

Can you provide a continuous time example under the proposed syntax?

The example from readme could look like this :

(def !input (atom 1))
(def main
  (let [<x (m/signal (m/watch !input))
        <y (m/signal (m/latest + <x <x))]
    (m/reduce (fn [_ y] (println y)) nil <y)))

from missionary.

Thanks, this will be a very useful addition. I've been using a function similar to memo in my application, and it is very useful to ensure a task only gets run once.

One question:

(def res (memo
            (m/sp
             (m/? (m/sleep 1000))
             (throw (ex-info "ERROR" {})))))
(m/? res) ;; wait 1s, throw exception
(m/? res) ;; (1) ??

What happens at (1) - does it wait for 1s again and then throw the exception, or throw the exception instantly?

from missionary.

What happens at (1) - does it wait for 1s again and then throw the exception, or throw the exception instantly?

At first glance it would make sense to me that any crashed publisher memoizes the error and rethrows it immediately to all current and future subscriptions.

from missionary.