Day #2

[cgrand]

What is the runtime model of the UI? A hierarchy of components.

When a delta arrives we get a long row, which can be split into stages (see rules in #4) , each stage mapping to a component into the hierarchy. If there's no component then it should be instantiated.

Let's imagine (syntax with #5):

[:ul
 (with [[item :item/title]]
   [:li (:item/title item) " is " (if (:item/done item) "done" "to do")])]

Here I count 4 templates:

• outer with
• inner with
• title
• done

Which would mean 3 queries

• [[item :item/title]]
• inner with has no query and should never have one
• [[item :item/title] [(get-else item :item/title nil) title]]
• [[item :item/title] [(get-else item :item/done nil) done]]

The last two would need to be differentiated by adding an id (the mount point id for example): [[item :item/title] [(ground :mount_421) mnt] [(get-else item :item/done nil) done]]

Thus such code should work:

(defn add [{:as component :keys [n instantiate]} row]
  (if (seq row)
    (let [k (subvec row 0 n)]
      (update-in component [:children k]
        (fn [child]
          (add (or child (instantiate k) (subvec row n))))))
    component))

It's too functional/persistent for something which is linear.

[cgrand]

By linear, I mean that actual nodes may be updated or mutated and we don’t care because they are never shared.