Add hello world example

dev/interactive/main.go

@@ -23,11 +23,20 @@ func main() {
 
 	ctx := context.Background()
 	en := engine.NewSizedEngine(dir, uint32(size))
-	err := en.Init(ctx)
+	cont, err := en.Init(ctx)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "engine init exited with error: %v\n", err)
 		os.Exit(1)
 	}
+	if !cont {
+		_, err = en.WriteResult(os.Stdout, ctx)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "dead init write error: %v\n", err)
+			os.Exit(1)
+		}
+		os.Stdout.Write([]byte{0x0a})
+		os.Exit(0)
+	}
 	err = engine.Loop(&en, os.Stdin, os.Stdout, ctx)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "loop exited with error: %v\n", err)