{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Using the experimental `nix` command\n",
    "\n",
    "The previous tutorial showed how to use Nix commands such as `nix-build` and `nix-env`. In this tutorial we'll use the new but still experimental `nix` command."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Building a package with `nix build`\n",
    "\n",
    "Instead of `nix-build` it is now possible to build using `nix build`. Note that, contrary to `nix-build`, no out-link is created by default.\n",
    "\n",
    "In the following example we create a `recipe.nix` file. In this case, our recipe is simple: we fetch the latest version of NixOS 19.09 and build a package from it, `hello`."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Writing recipe.nix\n"
     ]
    }
   ],
   "source": [
    "%%file recipe.nix\n",
    "with import (fetchTarball \"channel:nixos-19.09\") {};\n",
    "hello"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\u001b[K[\u001b[32;1m13.3\u001b[0m MiB DL]\n"
     ]
    }
   ],
   "source": [
    "! nix build -f recipe.nix"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "To obtain the path we can explicitly create a out-link"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\u001b[Klrwxrwxrwx 1 freddy users 54 Mar 28 11:34 result -> /nix/store/4w99qz14nsahk0s798a5rw5l7qk1zwwf-hello-2.10\n"
     ]
    }
   ],
   "source": [
    "! nix build -f recipe.nix -o result\n",
    "! ls -l result"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "We can run the `hello` command that is provided by it"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Hello, world!\n"
     ]
    }
   ],
   "source": [
    "! result/bin/hello"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Shell with specified packages with `nix run`\n",
    "\n",
    "The `nix run` command allows you to use a program temporarily; after closing the shell the program is \"gone\". Well, not really, it is still in the store but it can be garbage-collected again.\n",
    "\n",
    "The following one-liner calls `nix run`, tells it to use the Nix expressions found at `channel-nixos-20.03`, and then open a shell that has the Python 3 package. We also directly invoke `python3` using `--command` and tell `python3` to print `hello`."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\u001b[K[\u001b[32;1m13\u001b[0m copied (\u001b[32;1m99.4\u001b[0m MiB), \u001b[32;1m33.2\u001b[0m MiB DL]\n",
      "hello!\n"
     ]
    }
   ],
   "source": [
    "! nix run --file channel:nixos-20.03 python3 --command python3 -c 'print(\"hello!\")'"
   ]
  }
 ],
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  "kernelspec": {
   "display_name": "Python 3",
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    "name": "ipython",
    "version": 3
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   "file_extension": ".py",
   "mimetype": "text/x-python",
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