languages/python: add mypy (#1395)

Author: snoweuph

docs/manual/release-notes/rl-0.9.md

@@ -173,6 +173,9 @@
 
 - Added XML syntax highlighting, LSP support and formatting
 
+- Added [mypy](https://www.mypy-lang.org/) to `languages.python` for extra
+  diagnostics.
+
 - Added [tera](https://keats.github.io/tera/) language support (syntax
   highlighting only).
 

modules/plugins/languages/python.nix

@@ -11,7 +11,7 @@
   inherit (lib.modules) mkIf mkMerge;
   inherit (lib.types) enum package bool;
   inherit (lib.nvim.attrsets) mapListToAttrs;
-  inherit (lib.nvim.types) deprecatedSingleOrListOf;
+  inherit (lib.nvim.types) deprecatedSingleOrListOf diagnostics;
   inherit (lib.generators) mkLuaInline;
   inherit (lib.nvim.dag) entryBefore;
   inherit (lib.trivial) warn;
@@ -278,6 +278,14 @@
       '';
     };
   };
+  defaultDiagnosticsProvider = ["mypy"];
+  diagnosticsProviders = {
+    mypy = {
+      config = {
+        cmd = getExe' pkgs.mypy "mypy";
+      };
+    };
+  };
 in {
   options.vim.languages.python = {
     enable = mkEnableOption "Python language support";
@@ -335,6 +343,15 @@ in {
         '';
       };
     };
+
+    extraDiagnostics = {
+      enable = mkEnableOption "extra Python diagnostics" // {default = config.vim.languages.enableExtraDiagnostics;};
+      types = diagnostics {
+        langDesc = "Python";
+        inherit diagnosticsProviders;
+        inherit defaultDiagnosticsProvider;
+      };
+    };
   };
 
   config = mkIf cfg.enable (mkMerge [
@@ -404,5 +421,15 @@ in {
       vim.debugger.nvim-dap.enable = true;
       vim.debugger.nvim-dap.sources.python-debugger = debuggers.${cfg.dap.debugger}.dapConfig;
     })
+
+    (mkIf cfg.extraDiagnostics.enable {
+      vim.diagnostics.nvim-lint = {
+        enable = true;
+        linters_by_ft.python = cfg.extraDiagnostics.types;
+        linters =
+          mkMerge (map (name: {${name} = diagnosticsProviders.${name}.config;})
+            cfg.extraDiagnostics.types);
+      };
+    })
   ]);
 }