playground-622.ipynb

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   "source": [
    "# A PEP 622 Playground\n",
    "\n",
    "The purpose of this notebook is to facilitate interactive exploration of the proposed new syntax for _Structural Pattern Matching_ in Python 3.10, as described in [PEP-622](https://www.python.org/dev/peps/pep-0622).\n",
    "\n",
    "This notebook should be run with a kernel that uses a suitable version of Python with support for this PEP's new syntax. We start by making a quick sanity check that we're running at least version 3.10 of Python, if that's not the case you need to check your runtime environment.\n",
    "\n",
    "_Note:_ If you are new to Jupyter Notebooks, code cells (like the one below) can be executed by typing `Shift-Enter` inside the cell, or by using the \"play\" button (right-pointing triangle in the toolbar above)."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "import sys\n",
    "assert sys.version_info[:2] >= (3, 10)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "With that out of the way, let's introduce a very basic example that illustrates the syntax (and whether the cell below runs cleanly will be a good test that you have the right version of Python installed).\n",
    "\n",
    "We define a `dataclass` called `Point`, and a `whereis` function that matches points in different parts of the x-y plane:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "from dataclasses import dataclass\n",
    "\n",
    "@dataclass\n",
    "class Point:\n",
    "    x: int\n",
    "    y: int\n",
    "\n",
    "def whereis(point):\n",
    "    match point:\n",
    "        case Point(0, 0):\n",
    "            print(\"Origin\")\n",
    "        case Point(0, y):\n",
    "            print(f\"Y={y}\")\n",
    "        case Point(x, 0):\n",
    "            print(f\"X={x}\")\n",
    "        case Point():\n",
    "            print(\"Somewhere else\")\n",
    "        case _:\n",
    "            print(\"Not a point\")"
   ]
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  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "With this definition we can now test various kinds of points:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "X=1\n"
     ]
    }
   ],
   "source": [
    "whereis(Point(1, 0))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Origin\n"
     ]
    }
   ],
   "source": [
    "whereis(Point(0, 0))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Not a point\n"
     ]
    }
   ],
   "source": [
    "whereis(10)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Now start playing!\n",
    "\n",
    "You can explore these ideas further below. The `examples` directory contains some more sample code that you can run at the terminal (you can open a new terminal with the '+' icon or from the File menu), or you can try your own. The PEP contains full details on the syntax."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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