use watch script

Makefile

@@ -61,7 +61,7 @@ public/%: styleguide-app/%
 
 .PHONY: serve-public
 serve-public: public
-	./scripts/serve.sh public
+	./scripts/watch.sh
 
 # plumbing
 

scripts/watch.sh

@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# start a web server
+./scripts/serve.sh public &
+SERVER_PID=$!
+
+# start a watcher
+find src styleguide-app -type f -not -ipath '*elm-stuff*' | entr make public &
+WATCHER_PID=$!
+
+# wait for an interrupt and kill both of them
+cleanup() {
+    kill $SERVER_PID $WATCHER_PID
+}
+trap cleanup EXIT INT
+
+while : ; do sleep 10; done