diff --git a/e.rs b/e.rs
index 7ca3efe..fd0adfd 100644
--- a/e.rs
+++ b/e.rs
@@ -1,6 +1,13 @@
 #![feature(main)]
+#[cfg(feature = "functional")]
 #[main]
 fn e() {
+    std::iter::repeat('e').for_each(|e| print!("{}", e));
+}
+
+#[cfg(not(feature = "functional"))]
+#[main]
+fn e() -> ! {
     loop {
         print!("e");
     }