--- a/src/ast_dump.rs
+++ b/src/ast_dump.rs
@@ -197,6 +197,7 @@ impl to_string_able for expr {
             expr::Set(elts) => format!("{{{}}}", vec_to_strings_vec(elts).join(", ")),
             expr::SetComp(elt, generators) => format!("{{{} {}}}", elt.to_string(), vec_to_strings_vec(generators).join(" ")),
             expr::GeneratorExp(elt, generators) => format!("({} {})", elt.to_string(), vec_to_strings_vec(generators).join(" ")),
+            expr::Lambda(args, body) => format!("lambda {}: {}", args.to_string(), body.to_string()),
         }
     }
 }