wtf-is-reframe.md

wtf is re-frame

A look into the re-frame clojurescript lib.

work in progress

"re-frame is a pattern for writing SPAs in ClojureScript, using Reagent."

As taken from the readme,

To build a re-frame app, you:

• design your app's data structure (data layer)
• write and register subscription functions (query layer)
• write Reagent component functions (view layer)
• write and register event handler functions (control layer and/or state transition layer)

Quotes

MVC? or?

Perhaps it is a RACES framework - Reactive-Atom Component Event Subscription framework (I love the smell of acronym in the morning).

Or, if we distill to pure essence, DDATWD - Derived Data All The Way Down.

---

what is reactive programming?

https://github.com/Day8/re-frame#the-big-ratom

https://github.com/Day8/re-frame#how-flow-happens-in-reagent

https://github.com/Day8/re-frame#the-signal-graph

https://github.com/Day8/re-frame#event-flow

Data Layer

Query Layer

Subscribe

• Components should know as little as possible about the structure of app-db
• Subscription functions must return a value that changes over time (a Signal). They'll be returning a reaction or a ratom produced by a reaction.
• Components never source data directly from ap-db, instead they use a subscription.
• Subscriptions are only ever used by components (never event handlers).

Example

(defn greet         ;; outer, setup function, called once
  []
  (let [name-ratom  (subscribe [:name-query])]    ;; <---- subscribing happens here
     (fn []        ;; the inner, render function, potentially called many times.
         [:div "Hello" @name-ratom])))    

subscribe is always called like this:

(subscribe [query-id some optional query parameters])

View Layer

• Reagent components
• Pure functions
• Data in, Hiccup out. (DOM)

(defn greet
  []
  [:div "Hello ratoms and reactions"])

;;And if we call it:

(greet)
;; ==>  [:div "Hello ratoms and reactions"]

Control Layer / State Transition Layer