[Nix-dev] Python 3 as default

[Peter Simons]

Hi Moritz,

 > You almost never have python installed globally.

I absolutely do. I have both python 2 and 3 in my ~/.nix-profile and I
have all kinds of scripts that run "/usr/bin/env python" to find their
interpreter.


 > All packaged programs refer to one *specific* instance of python of
 > their choosing and it's only availale for themself, not anywhere
 > else.

This is true for builds running inside of Nix, but its oftentimes false
for scripts that users run outside of Nix, e.g. in their shell. 


 > Also note that it's generally discouraged to "globally" install a
 > package for development needs. Instead of globally installing
 > python3, firefox and gdb you write a `shell.nix` file in the project
 > directory.

I'm not sure what you mean by "globally discouraged", but I certainly
don't buy into that. I hardly ever use nix-shell and I don't want to, to
be honest, and I'd respond rather angrily to attempts from other people
to impose their preferred development style onto me.

Best regards,
Peter