Could not find type constructor `WebGL.Shader`

[Zinggi]

When trying to compile examples for my .obj file loader I ran into a strange issue:

elm-make: Could not find type constructor `WebGL.Shader` while checking types.
elm-make: thread blocked indefinitely in an MVar operation

After some investigations, I managed to reduce it into the following two files:

SSCCE

Needs two files (Main.elm and Shaders.elm)

Main.elm

module Main exposing (..)

import Html exposing (Html)
import Shaders


main =
    Html.text ""

Shaders.elm

module Shaders exposing (..)


frag =
    [glsl|

void main() {
    gl_FragColor = vec4(1.0);
}
|]

elm-package.json

{
    "version": "1.0.0",
    "summary": "helpful summary of your project, less than 80 characters",
    "repository": "https://github.com/user/project.git",
    "license": "BSD3",
    "source-directories": [
        "."
    ],
    "exposed-modules": [],
    "dependencies": {
        "elm-community/linear-algebra": "1.0.0 <= v < 2.0.0",
        "elm-community/webgl": "2.0.0 <= v <= 3.0.0",
        "elm-lang/core": "5.0.0 <= v < 6.0.0",
        "elm-lang/html": "2.0.0 <= v < 3.0.0"
    },
    "elm-version": "0.18.0 <= v < 0.19.0"
}

Steps to reproduce

Try to compile Main.elm:
elm make Main.elm

Workarounds

Variant 1

Create a new file Test.elm.

module Test exposing (..)

import Html

main = Html.text "test"

compile it:
elm make Test.elm

The previous error vanished, elm make Main.elm now succeeds.

Variant 2

This is more obvious:

Add import WebGL at the top of Shaders.elm

Now compiling works.

OS	browser	Elm version
arch linux	NA	elm-make 0.18 (Elm Platform 0.18.0)

[process-bot]

Thanks for the issue! Make sure it satisfies this checklist. My human colleagues will appreciate it!

Here is what to expect next, and if anyone wants to comment, keep these things in mind.

[marrony]

related #1322