Generate pin labels automatically

marker.nix

@@ -1,5 +1,25 @@
 { lib, config, ... }:
 let
+  # Returns the uppercased first label or number of a string
+  firstUpperAlnum =
+    str:
+      lib.mapNullable
+        lib.head (builtins.match "[^A-Z0-9]*([A-Z0-9]).*" (lib.toUpper str));
+
+  userType = lib.types.submodule (
+    { name, ... }: {
+      options = {
+        departure = lib.mkOption {
+          type = markerType;
+          default = {};
+        };
+      };
+
+      config = {
+        departure.style.label = lib.mkDefault (firstUpperAlnum name);
+      };
+    });
+
   markerType = lib.types.submodule {
     options = {
       location = lib.mkOption {
@@ -14,15 +34,6 @@ let
       };
     };
   };
-
-  userType = lib.types.submodule {
-    options = {
-      departure = lib.mkOption {
-        type = markerType;
-        default = {};
-      };
-    };
-  };
 in
 {
   options = {
@@ -39,12 +50,10 @@ in
     users = {
       manuel.departure = {
         location = "Switzerland";
-        style.label = "M";
       };
 
       ganondorf.departure =  {
         location = "Argentinia";
-        style.label = "G";
       };
     };