add separate instructions for Netlify builds

netlify.toml

@@ -1,3 +1,3 @@
 [build]
-command = "shake public"
+command = "script/netlify.sh"
 publish = "public"

script/netlify.sh

@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+set -xeuo pipefail
+
+# Netlify doesn't support building stuff via Haskell or
+# Nix. Those things are vaguely on the horizon (check the issues at
+# https://github.com/netlify/build-image) but for now it's way simpler to just
+# accept that Netlify will need separate instructions.
+
+# get our dependencies
+npm install
+npm install elm
+
+# make sure we're building into a clean folder
+if test -d public; then rm -rf public; fi
+mkdir public
+
+# build the interactive parts
+(cd styleguide-app && npx elm make Main.elm --output ../public/elm.js)
+npx browserify --entry styleguide-app/manifest.js --outfile public/bundle.js
+
+# copy assets
+cp -r styleguide-app/assets public/assets