gomp

(I'm just starting off with rust, so please be patient)

Is there an idiomatic way of writing the following as a one-liner, somehow informing rustc that it should keep the PathBuf around?

// nevermind the fully-qualified names
// they are there to clarify the code
// (that's what I hope at least)

let dir: std::path::PathBuf = std::env::current_dir().unwrap();
let dir: &std::path::Path   = dir.as_path();

// this won't do:
// let dir = std::env::current_dir().unwrap().as_path();

I do understand why rust complains that "temporary value dropped while borrowed" (I mean, the message says it all), but, since I don't really need the PathBuf for anything else, I was wondering if there's an idiomatic to tell rust that it should extend its life until the end of the code block.

I want to have my screen (the "dev" workspace) split in three "zones":

• on the left side, a tabbed group with all the text editors I start (ie. if I start a new one, it goes there in a new tab)
• on the top-right, a tabbed group of whatever many terminal I feel like launching
• on the bottom-right, my browsers (and possibly other stuff), in a group without tabs
• a key combination to cycle between: all three "zones" visible, text editors on the left - terminal on the right, text editors on the left - browser on the right, fullscreen browser

So far I've been looking at hyprland (for no particular reason except the hype) and I don't think I can do the above with it (I am by no means an expert, so... maybe it can actually be done?).

Do you know of any WM where it would be possible? (possibly, one with automatic splitting a-la bspwm, that I would use for the other workspaces)

I've been looking around for a scripting language that:

• has a cli interpreter
• is a "general purpose" language (yes, awk is touring complete but no way I'm using that except for manipulating text)
• allows to write in a functional style (ie. it has functions like map, fold, etc and allows to pass functions around as arguments)
• has a small disk footprint
• has decent documentation (doesn't need to be great: I can figure out most things, but I don't want to have to look at the interpter source code to do so)
• has a simple/straightforward setup (ideally, it should be a single executable that I can just copy to a remote system, use to run a script and then delete)

Do you know of something that would fit the bill?

Here's a use case (the one I run into today, but this is a recurring thing for me).

For my homelab I need (well, want) to generate a luhn mod n check digit (it's for my provisioning scripts to generate synchting device ids from their certificates).

I couldn't find ready-made utilities for this and I might actually need might a variation of the "official" algorithm (IIUC syncthing had a bug in their initial implementation and decided to run with it).

I don't have python (or even bash) available in all my systems, and so my goto language for script is usually sh (yes, posix sh), which in all honestly is quite frustrating for manipulating data.

While updating home-manager I got a notice that freeimage-unstable-2021-11-01 is marked as unsafe.

Since chances are it's used by something I never use, I'd like to know what I'm using that depends on it... any idea how to do it?

Also.. any idea why I have 4 copies of the freeimage stuff in my /nix/store? (I just run nix-collect-garbage -d and the 4 seem to be actually different):

❱ md5sum /nix/store/*freeimage*/lib/libfreeimage.a
67a0ce1cb5dd562473e27d7c88e8a9bd  /nix/store/6gi6hm57zngqnxb6p5dnxhjjcbr96lrk-freeimage-unstable-2021-11-01/lib/libfreeimage.a
5995e0affbfa28b63da7e997cb4dbe63  /nix/store/09nwykzzksc0zknflsyxyah5b67c2rsn-freeimage-unstable-2021-11-01/lib/libfreeimage.a
67a0ce1cb5dd562473e27d7c88e8a9bd  /nix/store/ikfiv4gpmcpyir7lsj45by653qcnvgyx-freeimage-unstable-2021-11-01/lib/libfreeimage.a
213a408e3c1fbb5dfa4491deebe05984  /nix/store/q2sc85f2hclgwl8m3qdw8rpbs44gzmah-freeimage-unstable-2021-11-01/lib/libfreeimage.a

This may be OT since strictly speaking it's about hardware... I trust it is ok to post it given the spirit of the community, but have my apologies and feel free to remove it if it's not.

I'm looking to replace my old Bose QC25, since they have recently died (after a long a fulfilling life), but it seems everything nowadays is bluetooth (which I don't mind) and require some proprietary app to turn ANC on/off (which I do mind... are physical buttons/switches become too expensive to include in your overpriced earbuds?).

Anyway... do you know of any headphones/earbuds that meet the following?

1. can be powered via wire or have batteries that last 12+hrs (long-haul flights)
2. have decent noise cancelling
3. don't require me to install a apps or can be used with some open source app (possibly with full functionality and straightforward to setup)
4. are not overly expensive (I have to buy 2 pairs and I'll only use them a few times a year when I fly)

I want to call the escapeSystemdPath (defined in nixpgs at nixos/lib/utils.nix) to derive the name of a systemd mount unit from the target path (eg. srv-my-dir.mount from /srv/my/dir), but I can't figure out how I can reference it... any ideas?

I'm playing around with nixos in a few VMs and at some point I realized I must have lost the swap configuration in one of my refactorings.

To my surprise, however, the VMs do use the swap partitions I had set up.

There is no mention on "swap" in my nix configuration (or in fstab) and no .swap units in /etc/systemd/system; I do however have a swap partition labelled "swap".

Turns out there is a systemd unit (albeit not a corresponding file) that sets up swap:

[root@vm1:~]# free -hw
               total        used        free      shared     buffers       cache   available
Mem:           2.8Gi       664Mi       955Mi       4.0Mi       3.0Mi       1.3Gi       2.0Gi
Swap:          3.7Gi          0B       3.7Gi

[root@vm1:~]# systemctl list-dependencies swap.target 
swap.target
● └─dev-disk-by\x2ddiskseq-1\x2dpart3.swap

I'm wondering where the unit comes from? Can I rely on this and never configure swap ever again?

I have an option that must be left with the default value when a certain flag (another option) is false.

I didn't find any example (let alone documentation) on how to implement this, so I've come up with two ideas:

option-that-errors-out-if-set-when-flag-is-false =
let
  default = if config.some-flag
          then "some default value for when flag is true"
          else "value that should not be changed when flag is false";
in lib.mkOption {
  type = lib.types.str;
  inherit default;
  apply = v: assert assertMsg (config.some-flag || v == default) "Do not set this option unless 'flag' is true";
          v;
};

option-that-ignores-value-when-flag-is-false =
let
  default = if config.some-flag
          then "some default value for when flag is true"
          else "value that should not be changed when flag is false";
in lib.mkOption {
  type = lib.types.str;
  inherit default;
  apply = v: if config.some-flag then v else default;
};

Which one do you think is "best" (cleaner, more idiomatic, etc..)?

Is apply the "right" place to validate options? Should I make a custom type instead? Should I approach this in some different way?

I'd like to set a "global" option from within a submodule, but the config I return is grafted into the "global" under the submodule "path" rather than at the root... any idea if it's somehow possible?

Er... I guess I didn't make a great job at explaining what I want to do... Some code will hopefully help.

In mymodule.nix I have:

{ lib, config, ... }: {

  options.myoption = lib.mkOption {
      type = lib.types.attrsOf (lib.types.submodule (
        import ./mysubmodule.nix
      ));
  };

}

and mysubmodule.nix is:

{ name, lib, config, ... }: {

options.mysubmoduleoption = {
  type = lib.types.str;
};

config = {
  # here I want to set a "global" option, say "systemd.mounts"
  # based on the value of "mymodule.name.mysubmoduleoption"
  # but it seems I can only set values under "mymodule.name" 
};

}

I'm trying to debug a module I'm writing with builtins.trace, but it's being more complicated than I anticipated.

Let's say I have a module:

{ config, lib, pkgs, modulesPath, ... }:

{

  config =
  let
    some-list = lib.attrsets.mapAttrsToList (n: v: {
        some-attr = "${n} ${v}";
    }) { n1 = "v1"; n2 = "v2"; };
  in {
    users.mutableUsers = builtins.trace (some-list) false;
  };

}

This will print

trace: [ <code> <code> ]

because builtins.trace (for whatever reason?) evaluates its first argument only shallowly.

Changing the trace expression to:

builtins.trace (builtins.toJSON some-list) false;

helps a lot, but as soon as one tries to print a long list or a structure with some complexity the output is completely unreadable, and it's not like it can easily be piped into jq (I mean... &| grep ^trace: | sed 's/trace: //' | jq works*, but there must be a "better" way?)

(*) in fish shell, IDK about bash

edit: It's not like I specifically want JSON output: any format will do (ideally, nix would be nice)

I need to generate a number of scripts in my configuration and make them into a single package (for ease of reference, because there are a lot of them).

So far, I'm creating the scripts via writeShellApplication, making them into packages via an overlay, merging them with buildEnv and then adding the resulting package to `systemPackages.

Something like:

nixpkgs.overlays = [ (final: prev: {
  my-hello-1 = final.writeShellApplication {
    name = "my-hello-1-script";
    text = "echo my hello wolrd 1";
  };
  my-hello-2 = final.writeShellApplication {
    name = "my-hello-2-script";
    text = "echo my hello wolrd 1";
  };
  my-hello-scripts = final.buildEnv {
    name = "my-hello-scripts";
    paths = [ final.my-hello-1 final.my-hello-2 ];
  };
}) ];

environment.systemPackages = [ pkgs.my-hello-scripts ];

This works, but I don't really need the my-hello-1 and my-hello-2 packages... can you think of a way to make do without needing them?