vim: add option programs.vim.settings

This option gathers basic Vim options into a single place. The idea is
to allow many options without making the Home Manager documentation
too verbose.

This also deprecates the options `programs.vim.lineNumbers` and
`programs.vim.tabSize`.

Fixes #69.

modules/misc/news.nix

@@ -255,6 +255,25 @@ in
           'xsession.windowManager.i3'.
         '';
       }
+
+      {
+        time = "2017-09-30T09:44:18+00:00";
+        condition = with config.programs.vim;
+          enable && (tabSize != null || lineNumbers != null);
+        message = ''
+          The options 'programs.vim.tabSize' and 'programs.vim.lineNumbers' have
+          been deprecated and will be removed in the near future.
+
+          The new and preferred way to configure tab size and line numbers is to
+          use the more general 'programs.vim.settings' option. Specifically,
+          instead of
+
+          - 'programs.vim.lineNumbers' use 'programs.vim.settings.number', and
+
+          - 'programs.vim.tabSize' use 'programs.vim.settings.tabstop' and
+            'programs.vim.settings.shiftwidth'.
+        '';
+      }
     ];
   };
 }

modules/programs/vim.nix

@@ -7,6 +7,36 @@ let
   cfg = config.programs.vim;
   defaultPlugins = [ "sensible" ];
 
+  knownSettings = {
+    background = types.enum [ "dark" "light" ];
+    expandtab = types.bool;
+    history = types.int;
+    number = types.bool;
+    relativenumber = types.bool;
+    shiftwidth = types.int;
+    tabstop = types.int;
+  };
+
+  vimSettingsType = types.submodule {
+    options =
+      let
+        opt = name: type: mkOption {
+          type = types.nullOr type;
+          default = null;
+          visible = false;
+        };
+      in
+        mapAttrs opt knownSettings;
+  };
+
+  setExpr = name: value:
+    let
+      v =
+        if isBool value then (if value then "" else "no") + name
+        else name + "=" + toString value;
+    in
+      optionalString (value != null) ("set " + v);
+
 in
 
 {
@@ -17,14 +47,22 @@ in
       lineNumbers = mkOption {
         type = types.nullOr types.bool;
         default = null;
-        description = "Whether to show line numbers.";
+        description = ''
+          Whether to show line numbers. DEPRECATED: Use
+          <varname>programs.vim.settings.number</varname>.
+        '';
       };
 
       tabSize = mkOption {
         type = types.nullOr types.int;
-        default = null; 
+        default = null;
         example = 4;
-        description = "Set tab size and shift width to a specified number of spaces.";
+        description = ''
+          Set tab size and shift width to a specified number of
+          spaces. DEPRECATED: Use
+          <varname>programs.vim.settings.tabstop</varname> and
+          <varname>programs.vim.settings.shiftwidth</varname>.
+        '';
       };
 
       plugins = mkOption {
@@ -37,6 +75,38 @@ in
         '';
       };
 
+      settings = mkOption {
+        type = vimSettingsType;
+        default = {};
+        example = literalExample ''
+          {
+            expandtab = true;
+            history = 1000;
+            background = "dark";
+          }
+        '';
+        description = ''
+          At attribute set of Vim settings. The attribute names and
+          corresponding values must be among the following supported
+          options.
+
+          <informaltable frame="none"><tgroup cols="1"><tbody>
+          ${concatStringsSep "\n" (
+            mapAttrsToList (n: v: ''
+              <row>
+                <entry><varname>${n}</varname></entry>
+                <entry>${v.description}</entry>
+              </row>
+            '') knownSettings
+          )}
+          </tbody></tgroup></informaltable>
+
+          See the Vim documentation for detailed descriptions of these
+          options. Note, use <varname>extraConfig</varname> to
+          manually set any options not listed above.
+        '';
+      };
+
       extraConfig = mkOption {
         type = types.lines;
         default = "";
@@ -57,12 +127,11 @@ in
 
   config = (
     let
-      optionalBoolean = name: val: optionalString (val != null) (if val then "set ${name}" else "unset ${name}");
-      optionalInteger = name: val: optionalString (val != null) "set ${name}=${toString val}";
       customRC = ''
-        ${optionalBoolean "number" cfg.lineNumbers}
-        ${optionalInteger "tabstop" cfg.tabSize}
-        ${optionalInteger "shiftwidth" cfg.tabSize}
+        ${concatStringsSep "\n" (
+          filter (v: v != "") (
+          mapAttrsToList setExpr (
+          builtins.intersectAttrs knownSettings cfg.settings)))}
 
         ${cfg.extraConfig}
       '';
@@ -76,9 +145,31 @@ in
         ];
       };
 
-    in mkIf cfg.enable {
-      programs.vim.package = vim;
-      home.packages = [ cfg.package ];
-    }
+    in mkIf cfg.enable (mkMerge [
+      {
+        programs.vim.package = vim;
+        home.packages = [ cfg.package ];
+      }
+
+      (mkIf (cfg.lineNumbers != null) {
+        warnings = [
+          ("'programs.vim.lineNumbers' is deprecated, "
+            + "use 'programs.vim.settings.number'")
+        ];
+
+        programs.vim.settings.number = cfg.lineNumbers;
+      })
+
+      (mkIf (cfg.tabSize != null) {
+        warnings = [
+          ("'programs.vim.tabSize' is deprecated, use "
+            + "'programs.vim.settings.tabstop' and "
+            + "'programs.vim.settings.shiftwidth'")
+        ];
+
+        programs.vim.settings.tabstop = cfg.tabSize;
+        programs.vim.settings.shiftwidth = cfg.tabSize;
+      })
+    ])
   );
 }