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+# nixos-config - My current NixOS configuration
+#
+# Copyright (C) 2025 Benedikt Peetz <benedikt.peetz@b-peetz.de>
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+# This file is part of my nixos-config.
+#
+# You should have received a copy of the License along with this program.
+# If not, see <https://www.gnu.org/licenses/gpl-3.0.txt>.
+{lib}: rec {
+  /*
+  Converts `number` from a binary number to a decimal one.
+
+  The input is indented to be a number composed only of `1`s and `0` (e.g., 10010.)
+
+  # Type
+
+  binaryToDecimal :: Int -> Int
+
+  # Arguments
+
+  number
+  : The sequence of `1`s and `0`s defining a binary number, in little endian.
+
+  # Examples
+
+  binaryToDecimal 1001
+  => 9
+  */
+  binaryToDecimal = number: let
+    binaryList =
+      builtins.map lib.strings.toInt (lib.lists.reverseList (lib.strings.stringToCharacters (builtins.toString number)));
+  in
+    builtins.foldl' (acc: num: acc + num) 0
+    (lib.lists.imap0 (index: elem: elem * (pow 2 index)) binaryList);
+
+  /*
+  Converts `string` to a (probably) unique numerical id.
+
+  This is achieved by hashing the string and returning the first six hex-digits
+  converted to a base 10 number.
+
+  # Type
+
+  idFromString :: String -> Int
+
+  # Arguments
+
+  string
+  : The string to use as seed for the id generation.
+
+  # Examples
+
+  idFromString "3d-printer"
+  => 10365713
+  */
+  idFromString = string: let
+    inputSeed =
+      builtins.concatStringsSep ""
+      (lib.lists.take 6
+        (lib.strings.stringToCharacters (builtins.hashString "sha256" string)));
+  in
+    lib.trivial.fromHexString inputSeed;
+
+  /*
+  source: https://github.com/NixOS/nix/issues/10387#issuecomment-2494597690
+
+  Raises the `base` to the power of `power`.
+
+  Considering the small input size and the lack of a built-in power function [2],
+  this naive power implementation should satisfy reasonable performance
+  requirements.
+
+  Due to the lack of a modulo and bitwise AND operator, it is questionable whether
+  the recursive exponentiation by squaring [1] implementation would even be
+  faster.
+
+  [1]: https://en.wikipedia.org/wiki/Exponentiation_by_squaring
+  [2]: https://github.com/NixOS/nix/issues/10387
+
+  # Type
+
+  pow :: Number -> Number -> Number
+
+  # Arguments
+
+  base
+  : The base number to be raised.
+
+  power
+  : The exponent to raise `base` to.
+
+  # Examples
+
+  pow 2 5
+  => 32
+  */
+  pow = base: power:
+    if power == 0
+    then 1
+    else if power > 0
+    then (base * (pow base (power - 1)))
+    else builtins.throw "Negative powers are not supported";
+
+  options = {
+    /*
+    Generate an enable option definition, that defaults to true.
+
+    This conveniently allows the composition of a “common” module set.
+
+    # Type
+
+    mkEnable :: String -> AttrSet
+
+    # Arguments
+
+    name
+    : The name to use in the option description.
+    */
+    mkEnable = name:
+      (lib.mkEnableOption name)
+      // {
+        default = true;
+      };
+  };
+}