qalculate: init module

modules/misc/news/2026/04/2026-04-22_17-29-21.nix

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+{
+  time = "2026-04-22T17:29:21+00:00";
+  condition = true;
+  message = ''
+    A new module is available: 'programs.qalculate'. Qalculate! is a
+    multi-purpose desktop calculator that is simple to use but
+    provides power and versatility normally reserved for complicated
+    math packages.
+  '';
+}

modules/programs/qalculate.nix

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+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+let
+  cfg = config.programs.qalculate;
+
+  iniFormat = pkgs.formats.ini { };
+in
+{
+  meta.maintainers = [ lib.maintainers.philocalyst ];
+
+  options.programs.qalculate = {
+    enable = lib.mkEnableOption "Qalculate!, a multi-purpose desktop calculator";
+
+    package = lib.mkPackageOption pkgs "libqalculate" {
+      nullable = true;
+      example = "pkgs.qalculate-gtk";
+    };
+
+    settings = lib.mkOption {
+      inherit (iniFormat) type;
+      default = { };
+      example = lib.literalExpression ''
+        {
+          General = {
+            precision = 10;
+            colorize = 1;
+            save_mode_on_exit = 1;
+            save_definitions_on_exit = 0;
+          };
+          Mode = {
+            angle_unit = 1;
+            number_base = 10;
+            min_deci = 0;
+            max_deci = -1;
+          };
+        }
+      '';
+
+      description = ''
+        Configuration written to
+        {file}`$XDG_CONFIG_HOME/qalculate/qalc.cfg`.
+
+        Settings are organized into two INI sections:
+
+        - `General` — persistence and display preferences (e.g.
+          `save_mode_on_exit`, `colorize`, `precision`).
+        - `Mode` — active calculator settings that mirror the options
+          accepted by the {command}`set` command in an interactive
+          {command}`qalc` session (e.g. `angle_unit`, `number_base`,
+          `min_deci`).
+
+        See {manpage}`qalc(1)` for the full list of available settings
+        and their accepted values.
+      '';
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    home.packages = lib.mkIf (cfg.package != null) [ cfg.package ];
+
+    xdg.configFile."qalculate/qalc.cfg" = lib.mkIf (cfg.settings != { }) {
+      source = iniFormat.generate "qalc.cfg" cfg.settings;
+    };
+  };
+}

tests/modules/programs/qalculate/default.nix

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+{
+  qalculate-empty-settings = ./qalculate-empty-settings.nix;
+  qalculate-with-settings = ./qalculate-with-settings.nix;
+}

tests/modules/programs/qalculate/qalculate-empty-settings.nix

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+{
+  programs.qalculate = {
+    enable = true;
+    settings = { };
+  };
+
+  nmt.script = ''
+    assertPathNotExists home-files/.config/qalculate/qalc.cfg
+  '';
+}

tests/modules/programs/qalculate/qalculate-with-settings-expected

@@ -0,0 +1,8 @@
+[General]
+colorize=1
+precision=10
+save_mode_on_exit=1
+
+[Mode]
+angle_unit=1
+number_base=10

tests/modules/programs/qalculate/qalculate-with-settings.nix

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+{
+  programs.qalculate = {
+    enable = true;
+    settings = {
+      General = {
+        colorize = 1;
+        precision = 10;
+        save_mode_on_exit = 1;
+      };
+      Mode = {
+        angle_unit = 1;
+        number_base = 10;
+      };
+    };
+  };
+
+  nmt.script = ''
+    assertFileExists home-files/.config/qalculate/qalc.cfg
+    assertFileContent \
+      home-files/.config/qalculate/qalc.cfg \
+      ${./qalculate-with-settings-expected}
+  '';
+}