Elm WebGL -- nothing gets rendered without AnimationFrame being involved.

elm-package.json

{
    "version": "1.0.0",
    "summary": "RUN!",
    "repository": "https://github.com/user/repo.git",
    "license": "MIT",
    "source-directories": [
        "."
    ],
    "exposed-modules": [],
    "dependencies": {
        "elm-community/elm-linear-algebra": "2.0.2 <= v < 3.0.0",
        "elm-community/elm-webgl": "3.0.0 <= v < 4.0.0",
        "elm-lang/animation-frame": "1.0.0 <= v < 2.0.0",
        "elm-lang/core": "4.0.1 <= v < 5.0.0",
        "elm-lang/html": "1.0.0 <= v < 2.0.0"
    },
    "elm-version": "0.17.0 <= v < 0.18.0"
}

Main.elm

module Main exposing (main)

import Math.Vector3 as Vec3 exposing (Vec3)
import Html as H exposing (Html)
import Html.App as App
import Html.Attributes as HA
import Time
import WebGL
import AnimationFrame


main : Program Never
main =
    App.program
        { init = () ! []
        , subscriptions =
            \_ ->
                if False then
                    AnimationFrame.diffs identity
                else if False then
                    Time.every (5 * Time.second) identity
                else
                    Sub.none
        , update = \_ _ -> () ! []
        , view = view
        }


view : a -> Html msg
view model =
    WebGL.toHtml
        [ HA.width 400
        , HA.height 300
        ]
        [ WebGL.render vertexShader fragmentShader heroVertices {} ]


type alias Vertex =
    { pos : Vec3 }


heroVertices : WebGL.Drawable Vertex
heroVertices =
    WebGL.Triangle
        [ ( { pos = Vec3.vec3 0 0 0 }
          , { pos = Vec3.vec3 1 1 0 }
          , { pos = Vec3.vec3 1 -1 0 }
          )
        ]
        |> Debug.log "triangle"


vertexShader : WebGL.Shader Vertex {} {}
vertexShader =
    [glsl|
        precision mediump float;

        attribute vec3 pos;

        void main() {
            gl_Position = vec4(0.5 * pos, 1);
        } |]


fragmentShader : WebGL.Shader {} {} {}
fragmentShader =
    [glsl|
        precision mediump float;

        void main() {
            gl_FragColor = vec4(0, 0, 1, 1);
        } |]