fix a bug in recur

Author: kaikalii

src/algorithm/recur.rs

@@ -106,6 +106,11 @@ pub fn recur(is_leaf: SigNode, children: SigNode, combine: SigNode, env: &mut Ui
                 Value::from_row_values(child_nodes, env)?
             };
             if call_combine {
+                env.push_all(
+                    (consts.iter())
+                        .take(combine.sig.args().saturating_sub(2))
+                        .cloned(),
+                );
                 env.push(children_value);
                 if combine.sig.args() > 1 {
                     env.push(value);

src/check.rs

@@ -426,8 +426,11 @@ impl VirtualEnv {
                     self.handle_args_outputs(f.args(), f.outputs() + 1);
                 }
                 Recur => {
-                    let [_is_leaf, children, _combine] = get_args(args)?;
-                    let args = children.args();
+                    let [is_leaf, children, combine] = get_args(args)?;
+                    let args = is_leaf
+                        .args()
+                        .max(children.args())
+                        .max(combine.args().saturating_sub(1).max(1));
                     self.handle_args_outputs(args, 1);
                 }
                 Sys(SysOp::ReadLines) => {