❯ nix build -Lv
warning: Git tree '/home/hhefesto/src/Tontine/robo-actuary' is dirty
error:
       … while calling the 'derivationStrict' builtin
         at <nix/derivation-internal.nix>:37:12:
           36|
           37|   strict = derivationStrict drvAttrs;
             |            ^
           38|

       … while evaluating derivation 'user-account-service-0.1.0.0'
         whose name attribute is located at /nix/store/qmm7hgw60vp7vj9lma95hl329d0j3n6n-source/pkgs/stdenv/generic/make-derivation.nix:438:13

       … while evaluating attribute 'buildInputs' of derivation 'user-account-service-0.1.0.0'
         at /nix/store/qmm7hgw60vp7vj9lma95hl329d0j3n6n-source/pkgs/stdenv/generic/make-derivation.nix:493:13:
          492|             depsHostHost = elemAt (elemAt dependencies 1) 0;
          493|             buildInputs = elemAt (elemAt dependencies 1) 1;
             |             ^
          494|             depsTargetTarget = elemAt (elemAt dependencies 2) 0;

       (stack trace truncated; use '--show-trace' to show the full, detailed trace)

       error: Package ‘tt-common-0.1.0.0’ in /nix/store/zdxbv7why72l2plp920vgxviinawgw02-cabal2nix-tt-common/default.nix:21 has an unfree license (‘unfree’), refusing to evaluate.

       a) To temporarily allow unfree packages, you can use an environment variable
          for a single invocation of the nix tools.

            $ export NIXPKGS_ALLOW_UNFREE=1

          Note: When using `nix shell`, `nix build`, `nix develop`, etc with a flake,
                then pass `--impure` in order to allow use of environment variables.

       b) For `nixos-rebuild` you can set
         { nixpkgs.config.allowUnfree = true; }
       in configuration.nix to override this.

       Alternatively you can configure a predicate to allow specific packages:
         { nixpkgs.config.allowUnfreePredicate = pkg: builtins.elem (lib.getName pkg) [
             "tt-common"
           ];
         }

       c) For `nix-env`, `nix-build`, `nix-shell` or any other Nix command you can add
         { allowUnfree = true; }
       to ~/.config/nixpkgs/config.nix.

  outputs = inputs@{ self, nixpkgs, flake-parts, ... }:
    flake-parts.lib.mkFlake { inherit inputs; } {
      systems = nixpkgs.lib.systems.flakeExposed;
      imports = [ inputs.haskell-flake.flakeModule ];

      perSystem = { self', system, ... }:
      let
        pkgs = import nixpkgs {
          inherit system;
          config = {
            allowUnfree = true;
            allowUnfreePredicate = pkg: builtins.elem (pkgs.lib.getName pkg) [
             "tt-common"
            ];
            permittedInsecurePackages = [
              "beekeeper-studio-5.1.5"
            ];
          };
        };
      in {

        haskellProjects.default = { ...