Make PartialEq work with reference lhs
diff --git a/syntax/atom.rs b/syntax/atom.rs
index 903f561..9fb6554 100644
--- a/syntax/atom.rs
+++ b/syntax/atom.rs
@@ -54,3 +54,15 @@
         }
     }
 }
+
+impl PartialEq<Atom> for &Ident {
+    fn eq(&self, atom: &Atom) -> bool {
+        *self == atom
+    }
+}
+
+impl PartialEq<Atom> for &Type {
+    fn eq(&self, atom: &Atom) -> bool {
+        *self == atom
+    }
+}