3_scripting.ipynb

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 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Scripts and Smart Contracts"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Turing completeness"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "from pprint import pprint\n",
    "from blockchains.mark_2.blockchain import Blockchain"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Let's create a Blockchain"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "blockchain = Blockchain()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Let's create a locking script (the \"domain logic\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "locking_script = \"output = a + b if a > 3 else (2 * a) + b\""
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### First entry: the good one"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# First\n",
    "unlocking_script_1 = \"\"\"\n",
    "a = 1\n",
    "b = 1\n",
    "\"\"\"\n",
    "blockchain.add_transaction(unlocking_script_1, locking_script)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "blockchain.mine()\n",
    "pprint(blockchain.get_chain())"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Second entry: another good one"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Second\n",
    "unlocking_script_2 = \"\"\"\n",
    "a = 4\n",
    "b = 2\n",
    "\"\"\"\n",
    "blockchain.add_transaction(unlocking_script_2, locking_script)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "blockchain.mine()\n",
    "pprint(blockchain.get_chain())"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## The Ethical problem"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### The expert"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "unlocking_script_3 = \"\"\"\n",
    "a = I want 4!\n",
    "b = 2\n",
    "\"\"\"\n",
    "blockchain.add_transaction(unlocking_script_3, locking_script)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "blockchain.mine()\n",
    "pprint(blockchain.get_chain())"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## The (not so) technical problem"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Sorry Alan Turing..."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### The genius"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**WARNING**: This cell creates an infinite loop"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "unlocking_script_4 = \"\"\"\n",
    "while True:\n",
    "    print('I donated 4!')\n",
    "\"\"\"\n",
    "blockchain.add_transaction(unlocking_script_4, locking_script)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "blockchain.mine()\n",
    "pprint(blockchain.get_chain())"
   ]
  }
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