changed impl

src/list.rs

@@ -1,3 +1,5 @@
+use std::fmt::Display;
+
 use crate::value::Value;
 
 /// Single-linked list
@@ -14,8 +16,13 @@ impl<'a> List<'a> {
             .rev()
             .fold(Self::Nil, |list, next| Self::Cons(next, Box::new(list)))
     }
+}
 
-    pub fn iter(&self) -> Iter<'_, '_> {
+impl<'l, 'v> IntoIterator for &'l List<'v> {
+    type Item = &'l Value<'v>;
+    type IntoIter = Iter<'l, 'v>;
+
+    fn into_iter(self) -> Self::IntoIter {
         Iter(self)
     }
 }