quirk: explicit resource management doesn't work like defer in go

experiment.ipynb

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   "source": [
    "# explicit resource management: unexpected recursive behavior\n",
    "\n",
    "in go, a defer that is run inside a child function runs before the parent defer. javascript's [explicit resource management](https://tc39.es/proposal-explicit-resource-management/) doesn't work like this."
   ]
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     "name": "stdout",
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     "text": [
      "a start\n",
      "b start\n",
      "a end\n",
      "b end\n"
     ]
    }
   ],
   "source": [
    "function a() {\n",
    "\tconsole.log(\"a start\")\n",
    "\treturn {\n",
    "\t\t[Symbol.dispose]: () => {\n",
    "\t\t\tconsole.log(\"a end\")\n",
    "\t\t}\n",
    "\t}\n",
    "}\n",
    "\n",
    "function b() {\n",
    "\tusing A = a()\n",
    "\tconsole.log(\"b start\")\n",
    "\treturn {\n",
    "\t\t[Symbol.dispose]: () => {\n",
    "\t\t\tconsole.log(\"b end\")\n",
    "\t\t}\n",
    "\t}\n",
    "}\n",
    "\n",
    "using B = b()\n",
    "\n",
    "/* output:\n",
    "a start\n",
    "b start\n",
    "a end\n",
    "b end\n",
    "*/"
   ]
  },
  {
   "cell_type": "markdown",
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   "source": [
    "a workaround is to not use `using` in the parent function, and manually call the dispose function"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "a start\n",
      "b start\n",
      "b end\n",
      "a end\n"
     ]
    }
   ],
   "source": [
    "function a() {\n",
    "\tconsole.log(\"a start\")\n",
    "\treturn {\n",
    "\t\t[Symbol.dispose]: () => {\n",
    "\t\t\tconsole.log(\"a end\")\n",
    "\t\t}\n",
    "\t}\n",
    "}\n",
    "\n",
    "function b() {\n",
    "\tconst A = a()\n",
    "\tconsole.log(\"b start\")\n",
    "\treturn {\n",
    "\t\t[Symbol.dispose]: () => {\n",
    "\t\t\tconsole.log(\"b end\")\n",
    "\t\t\tA[Symbol.dispose]()\n",
    "\t\t}\n",
    "\t}\n",
    "}\n",
    "\n",
    "using B = b()\n",
    "/* output:\n",
    "a start\n",
    "b start\n",
    "b end\n",
    "a end\n",
    "*/"
   ]
  }
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