matplotlib: add module

(cherry picked from commit 6a244b3a8d)

modules/misc/news.nix

@@ -929,6 +929,13 @@ in
           A new module is available: 'programs.opam'.
         '';
       }
+
+      {
+        time = "2019-01-18T00:21:56+00:00";
+        message = ''
+          A new module is available: 'programs.matplotlib'.
+        '';
+      }
     ];
   };
 }

modules/modules.nix

@@ -60,6 +60,7 @@ let
     (loadModule ./programs/jq.nix { })
     (loadModule ./programs/lesspipe.nix { })
     (loadModule ./programs/man.nix { })
+    (loadModule ./programs/matplotlib.nix { })
     (loadModule ./programs/mbsync.nix { })
     (loadModule ./programs/mercurial.nix { })
     (loadModule ./programs/msmtp.nix { })

modules/programs/matplotlib.nix

@@ -0,0 +1,64 @@
+{ config, lib, ... }:
+
+with lib;
+
+let
+
+  cfg = config.programs.matplotlib;
+
+  formatLine = o: n: v:
+    let
+      formatValue = v:
+        if isBool v then (if v then "True" else "False")
+        else toString v;
+    in
+      if isAttrs v
+      then concatStringsSep "\n" (mapAttrsToList (formatLine "${o}${n}.") v)
+      else (if v == "" then "" else "${o}${n}: ${formatValue v}");
+
+in
+
+{
+  meta.maintainers = [ maintainers.rprospero ];
+
+  options.programs.matplotlib = {
+    enable = mkEnableOption "matplotlib, a plotting library for python";
+
+    config = mkOption {
+      default = { };
+      type = types.attrs;
+      description = ''
+        Add terms to the <filename>matplotlibrc</filename> file to
+        control the default matplotlib behavior.
+      '';
+      example = literalExample  ''
+        {
+          backend = "Qt5Agg";
+          axes = {
+            grid = true;
+            facecolor = "black";
+            edgecolor = "FF9900";
+          };
+          grid.color = "FF9900";
+        }
+      '';
+    };
+
+    extraConfig = mkOption {
+      type = types.lines;
+      default = "";
+      description = ''
+        Additional commands for matplotlib that will be added to the
+        <filename>matplotlibrc</filename> file.
+      '';
+    };
+  };
+
+  config = mkIf cfg.enable {
+    xdg.configFile."matplotlib/matplotlibrc".text =
+      concatStringsSep "\n" ([]
+        ++ mapAttrsToList (formatLine "") cfg.config
+        ++ optional (cfg.extraConfig != "") cfg.extraConfig
+      ) + "\n";
+  };
+}