complete push

src/main.rs

@@ -1,16 +1,17 @@
-fn main() {
-    
-}
+fn main() {}
 
+#[derive(Debug)]
 pub struct List {
-    head: Link
+    head: Link,
 }
 
+#[derive(Debug)]
 enum Link {
     Empty,
     More(Box<Node>),
 }
 
+#[derive(Debug)]
 struct Node {
     elem: i32,
     next: Link,
@@ -24,9 +25,10 @@ impl List{
     pub fn push(&mut self, elem: i32) {
         let new_node = Node {
             elem: elem,
-            next: std::mem::replace(&mut self.head, Link::Empty)
+            next: std::mem::replace(&mut self.head, Link::Empty),
         };
+        self.head = Link::More(Box::new(new_node));
+    }
 }
 
-}