Please add :first-dispatch-n

[jeaye]

I have implemented this in re-frame-rules, a fork re-frame-async-flow-fx which tackles the problem of state tracking and cyclical flows by providing a declarative, non-stateful approach to binding rules. My goal is to get as much of these small improvements back into re-frame-async-flow-fx so we don't have forks lying around.

A new fn get-dispatch-n, as shown here: https://github.com/jeaye/re-frame-rules/blob/36811b3dfc3f56079209ed0f9341cb99fa79fa36/src/com/jeaye/re_frame_rules.cljs#L80-L87

Used in two places:

1. massage-rule: https://github.com/jeaye/re-frame-rules/blob/36811b3dfc3f56079209ed0f9341cb99fa79fa36/src/com/jeaye/re_frame_rules.cljs#L99

2. make-rules-event-handler: https://github.com/jeaye/re-frame-rules/blob/36811b3dfc3f56079209ed0f9341cb99fa79fa36/src/com/jeaye/re_frame_rules.cljs#L127

The use case is, in case it isn't obvious, for firing off a number of events and then handling their responses as they come in. This is much more useful in a non-stateful rule set, since you're just saying "When this happens, do this" and when it happens doesn't matter. Real-world example:

(def initialize-rules
  {:id ::initialize
   :first-dispatch-n [[::subscribe-for-refreshes]
                      [::do-refresh-token]
                      [::do-find-notification]]
   :rules [{:when :seen-any?
            :events [::no-notification-found
                     ::notification-found]
            :dispatch [::success-initialize]
            :unbind? true}
           {:when :seen-any?
            :events [::fail-refresh-token
                     ::fail-find-notification]
            :dispatch [::fail-initialize]
            :unbind? true}]})

(reg-spec-event-fx
  ::do-initialize
  [db ::d/app-db]
   {::rules/bind initialize-rules})

This would also be an indirect solution to #12.

[bhb]

👍