Re: [Nix-dev] nix-shell pro/con (was: Python 3 as default)

2017-02-23 Thread Thomas Tuegel 
Profpatsch  writes:
> On 17-02-15 09:10pm, Ricardo M. Correia wrote:
>> With nix-shell, I risk having the packages I need become outdated (without
>> me noticing) and/or become garbage collected (which I do every day
>> automatically) and unavailable if I lose Internet access (e.g. because I'm
>> traveling).
>
> I think you are confusing nix-env and nix-shell; nix-shell can’t have
> “outdated” packages, it will use what you specify.
>
> packages being not cached is a largely orthogonal problem;
> for example it would be quite easy to create a script that fetches
> the nix-shell deps for all your projects and creates a folder with
> gc-roots.

The next version of cabal-install will perform this caching for you
automatically. It uses your shell.nix (if present) and adds GC roots for
the results. Your environment is not garbage collected or updated unless
you clear out the work directory or modify the shell.nix.

This is not relevant to the discussion of Python interpreters, but I
thought it would be of general interest.

Regards,
Thomas
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Re: [Nix-dev] nix-shell pro/con (was: Python 3 as default)

2017-02-15 Thread Andreas Herrmann 
On Wednesday 15 February 2017 22:08:26 Profpatsch wrote:
> On 17-02-15 09:10pm, Ricardo M. Correia wrote:
> > Personally, I try to avoid using "nix-shell" as much as possible because I
> > want "nixos-rebuild switch" to atomically install (and upgrade) all the
> > software that I usually need, including development packages.
> > 
> > With nix-shell, I risk having the packages I need become outdated (without
> > me noticing) and/or become garbage collected (which I do every day
> > automatically) and unavailable if I lose Internet access (e.g. because I'm
> > traveling).
>
> packages being not cached is a largely orthogonal problem;
> for example it would be quite easy to create a script that fetches
> the nix-shell deps for all your projects and creates a folder with
> gc-roots.

I've written such a script a while ago:
https://gist.github.com/aherrmann/51b56283f9ed5853747908fbab907316

It places the gcroots in separate folders under `~/.nix-shell`.
If you run it as `pnix-shell -c` it will reevaluate the Nix expression.
This way you can enforce updates.
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Re: [Nix-dev] nix-shell pro/con (was: Python 3 as default)

2017-02-15 Thread Profpatsch 
On 17-02-15 09:10pm, Ricardo M. Correia wrote:
> Personally, I try to avoid using "nix-shell" as much as possible because I
> want "nixos-rebuild switch" to atomically install (and upgrade) all the
> software that I usually need, including development packages.
> 
> With nix-shell, I risk having the packages I need become outdated (without
> me noticing) and/or become garbage collected (which I do every day
> automatically) and unavailable if I lose Internet access (e.g. because I'm
> traveling).

I think you are confusing nix-env and nix-shell; nix-shell can’t have
“outdated” packages, it will use what you specify.

packages being not cached is a largely orthogonal problem;
for example it would be quite easy to create a script that fetches
the nix-shell deps for all your projects and creates a folder with
gc-roots.

For long-running projects I use `git worktree` to have a stable
checkout. If you want to get fancy you could set up a hydra
if you want to follow e.g. stable with your own patches applied.

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