Merge pull request #17 from JohanWinther/elm-debug-from-env

Add support for `ELM_DEBUG` environment variable

Author: hojberg

README.md

@@ -6,7 +6,7 @@ This is the UI you see when you type `ui` into `ucm`.
 
 ## Running Development Server
 
-🔔 You should only need to run the UI development server if you're contributing to the UI. If you just want to run the UI to see your Unison codebase, it should either come pre-installed with `ucm` or if you built from source can be downloaded with a script: `./dev-ui-install.hs` from the `unison` repository ([Running Unison](https://github.com/unisonweb/unison/blob/trunk/development.markdown#running-unison)).
+> 🔔 You should only need to run the UI development server if you're contributing to the UI. If you just want to run the UI to see your Unison codebase, it should either come pre-installed with `ucm` or if you built from source it can be downloaded with a script: `./dev-ui-install.hs` from the `unison` repository ([Running Unison](https://github.com/unisonweb/unison/blob/trunk/development.markdown#running-unison)).
 
 1. Start `ucm` (the executable is `unison` instead of `ucm` if you built the [unison repository](https://github.com/unisonweb/unison) from source) in headless mode: `ucm headless`, and copy the API URL (this URL
    is uniquely generated by `ucm` at start-up) from the `ucm` start-up output
@@ -19,6 +19,8 @@ This is the UI you see when you type `ui` into `ucm`.
 
 4. Visit `http://localhost:1234` in a browser.
 
+> 💡 Set the environment variable `ELM_DEBUG=1` before starting the dev server to enable Elm's time-travelling debugger.
+
 ## Dependencies
 
 This depends on the [ui-core package](https://github.com/unisonweb/ui-core) via

webpack.dev.js

@@ -4,6 +4,7 @@ const postcssPresetEnv = require("postcss-preset-env");
 const FaviconsWebpackPlugin = require("favicons-webpack-plugin");
 
 const API_URL = process.env.API_URL || "127.0.0.1:8080";
+const ELM_DEBUG = process.env.ELM_DEBUG || false;
 const UI_CORE_SRC = "elm-stuff/gitdeps/github.com/unisonweb/ui-core/src";
 
 module.exports = {
@@ -63,7 +64,7 @@ module.exports = {
           {
             loader: "elm-webpack-loader",
             options: {
-              debug: false,
+              debug: ELM_DEBUG,
               cwd: __dirname,
             },
           },