Lustre Animation

The basic usage is

• keep 1 Animations value
• add animations by some trigger
• call animation.cmd() on your value and let your lustre update() return it. This will cause a dispatch on the next JS animation frame, unless all animations have finished (and auto-removed)
• update your value
• evaluate for each animation you are interested in.

e.g. like this:

import lustre/animation as a

pub type Msg {
    Trigger
    Tick(Float)
}

pub fn update(model: Model, msg: Msg) {
    let m = case msg of {
        Trigger -> {
            let new_anim = a.add(model.animations, "id", 1.0, 2.0, 0.250)
            Model(1.0, animations: new_anim)
        }
        Tick(t) -> {
            let new_anim = a.tick(model.animations, t)
            let new_value = a.value(new_anim, "id", model.value)
            Model(new_value, new_anim)
        }
    }
    #(m, animation.cmd(m.animations, Tick))
}

In the above type Model, init and render have been omitted. There are fully functional examples animations in the test/ directory, which you can build by

gleam test
npx webpack build ./test/example_XYZ.mjs --mode=development
````

and then pointing your browser to `./dist/index.html`

Rerun webpack with another example and reload.

## TODO
* `every(Minute)`, etc
* `after(seconds: 2.5)`
* quadratic, cubic, etc interpolators
* Compose animations
  `from("anim", 1.0) |> after(0.250) |> cubic(3.0, 0.250) |> after(0.250) |> quadr(2.0, 0.250)`