@wasser: It's ok to use lazy seqs in hiccup. Hiccup "realizes" them

I figured it was something like that.

is there a simple way to get the previous value of a local component state ratom?

since reagent handles the swap! -> render on a deref of a changed input, is there a way to get what used to be in the atom?

@lwhorton: store the outgoing value when you swap 🙂

i found a tricker way that abuses react

an external component subscribes, then immediately hands over its deref’d subscription to an internal component, that internal uses reagent/create-class

that gives me access to prev/next on :component-will-update, and allows me to utilize more ratoms internally to get full control

(the things we do for animations….)

@lwhorton: that seems entirely reasonable. another thing you could do is capture another atom in a form-2 components closure, and use it to record "current" values during render, which will then be "previous" values on next render