fix

src/eval.js

@@ -447,7 +447,7 @@ export const eval_codestring = (codestring, scope) =>
     `
   ))(codestring, scope)
 
-const get_args_scope = (fn_node, args) => {
+const get_args_scope = (fn_node, args, closure) => {
   const arg_names = 
     collect_destructuring_identifiers(fn_node.function_args)
     .map(i => i.value)
@@ -464,7 +464,10 @@ const get_args_scope = (fn_node, args) => {
   */
   const codestring = `(([${destructuring}]) => [${arg_names.join(',')}])(__args)`
 
-  const {ok, value, error} = eval_codestring(codestring, {__args: args})
+  const {ok, value, error} = eval_codestring(codestring, {
+    ...closure,
+    __args: args,
+  })
 
   if(!ok) {
     // TODO show exact destructuring error
@@ -1142,7 +1145,11 @@ export const eval_frame = (calltree_node, modules) => {
   } else {
     // TODO default values for destructuring can be function calls
 
-    const args_scope_result = get_args_scope(node, calltree_node.args)
+    const args_scope_result = get_args_scope(
+      node, 
+      calltree_node.args,
+      calltree_node.fn.__closure
+    )
 
     // TODO fine-grained destructuring error, only for identifiers that
     // failed destructuring

test/test.js

@@ -820,6 +820,23 @@ export const tests = [
     assert_equal(frame.children[0].children[0].children[0].result.value, [1,2,3])
   }),
 
+  test('eval_frame default arg', () => {
+    const code = `
+      const x = 1
+      function y(z = x) {
+        return z 
+      }
+      y()
+    `
+    const tree = eval_tree(code)
+    const frame = eval_frame(tree.children[0])
+    assert_equal(
+      // value for z in return statement
+      frame.children[1].children[0].children[0].result.value, 
+      1
+    )
+  }),
+
   test('module not found', () => {
     const parsed = parse_modules(
       'a',
@@ -3174,6 +3191,7 @@ const y = x()`
     patch_builtin('random', null)
   }),
 
+
   test('record io cache discarded if args does not match', async () => {
     // Patch fetch
     patch_builtin('fetch', async () => 'first')