Fix package fetching for nixos-25.11 and nixos-unstable

[natsukium]

Summary

nixpkgs 25.11+ removed pkgs.recurseIntoAttrs, so nix-env -qaP --json fails for nixos-25.11, nixpkgs-25.11-darwin, nixos-unstable, and nixpkgs-unstable — no packages are indexed for those channels.
Inline recurseForDerivations = true in src/Nix.hs to restore fetching across every indexed channel.

Cause

Nixpkgs commit 03bb7d81954d "all-packages: do not export lib functions from pkgs" (2025-10-30) moved recurseIntoAttrs out of the pkgs/top-level/all-packages.nix result attrset, so super.recurseIntoAttrs in packageOverrides now raises attribute 'recurseIntoAttrs' missing.

Why not switch to super.lib.recurseIntoAttrs?

lib.recurseIntoAttrs was added in 8935bfb4ac36 (2019-09-11), so it is missing from every release before 20.09.
This project indexes from nixos-17.03 upward, so neither super.recurseIntoAttrs (gone in 25.11+) nor super.lib.recurseIntoAttrs (missing pre-20.09) alone covers the full range.

recurseForDerivations = true is the underlying mechanism of recurseIntoAttrs itself (see lib/attrsets.nix) and has been stable across every indexed revision.

Verification

Reproduced against nixos-25.11 HEAD (c7f47036d3df2add644c46d712d14262b7d86c0c) using the same nix-env -qaP --json invocation src/Nix.hs runs per commit.

Before (current config with super.recurseIntoAttrs):

$ nix-env -qaP --json \
    -f https://github.com/NixOS/nixpkgs/archive/c7f47036d3df2add644c46d712d14262b7d86c0c.tar.gz \
    --arg config '{ allowAliases = false; packageOverrides = super: {
      haskellPackages = super.recurseIntoAttrs super.haskellPackages;
      rPackages       = super.recurseIntoAttrs super.rPackages;
    }; }' > /dev/null
error: attribute 'recurseIntoAttrs' missing
# exit 1

After (patched config with inlined recurseForDerivations = true):

$ nix-env -qaP --json \
    -f https://github.com/NixOS/nixpkgs/archive/c7f47036d3df2add644c46d712d14262b7d86c0c.tar.gz \
    --arg config '{ allowAliases = false; packageOverrides = super: {
      haskellPackages = super.haskellPackages // { recurseForDerivations = true; };
      rPackages       = super.rPackages       // { recurseForDerivations = true; };
    }; }' | jq length
127054
# exit 0

Cross-check on the oldest indexed release nixos-17.03 (2c1838ab99b086dccad930e8dcc504b867149a0c) — where super.lib.recurseIntoAttrs would not exist — with the same patched config:

$ nix-env -qaP --json \
    -f https://github.com/NixOS/nixpkgs/archive/2c1838ab99b086dccad930e8dcc504b867149a0c.tar.gz \
    --arg config '{ allowAliases = false; packageOverrides = super: {
      haskellPackages = super.haskellPackages // { recurseForDerivations = true; };
      rPackages       = super.rPackages       // { recurseForDerivations = true; };
    }; }' | jq length
36363
# exit 0

related to #58

[unoukujou]

Thanks @natsukium I came here to see why the site no longer gets updated so nice to see this PR

@lazamar any chance to fix? The site was very useful, and still is for older stuff but a shame there is many packages missing now