diff --git a/src/ast/types.rs b/src/ast/types.rs
index 31551f4..88b36f6 100644
--- a/src/ast/types.rs
+++ b/src/ast/types.rs
@@ -276,25 +276,25 @@ impl std::fmt::Display for Expr {
             },
             Expr::Func(_) => string.push_str("<fn>"),
             Expr::Record(map) => {
-                string.push_str("{");
+                string.push('{');
                 for (key, val) in map {
                     string.push_str(&format!(" .{}: {},", key.0, val));
                 }
-                if map.len() > 0 {
+                if !map.is_empty() {
                     string.push_str(" }");
                 } else {
-                    string.push_str("}");
+                    string.push('}');
                 }
             }
             Expr::Vector(vec) => {
-                string.push_str("[");
+                string.push('[');
                 for val in vec {
                     string.push_str(&format!(" {},", val));
                 }
-                if vec.len() > 0 {
+                if !vec.is_empty() {
                     string.push_str(" ]");
                 } else {
-                    string.push_str("]");
+                    string.push(']');
                 }
             }
             _ => {}