#!/usr/bin/env python
# coding: utf-8

# # Using the experimental `nix` command
# 
# 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.

# ## Building a package with `nix build`
# 
# 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.
# 
# 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`.

# In[1]:


get_ipython().run_cell_magic('file', 'recipe.nix', 'with import (fetchTarball "channel:nixos-19.09") {};\nhello\n')


# In[2]:


get_ipython().system(' nix build -f recipe.nix')


# To obtain the path we can explicitly create a out-link

# In[3]:


get_ipython().system(' nix build -f recipe.nix -o result')
get_ipython().system(' ls -l result')


# We can run the `hello` command that is provided by it

# In[4]:


get_ipython().system(' result/bin/hello')


# ## Shell with specified packages with `nix run`
# 
# 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.
# 
# 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`.

# In[5]:


get_ipython().system(' nix run --file channel:nixos-20.03 python3 --command python3 -c \'print("hello!")\'')