Add mypy to python flake

python/.gitignore

@@ -1 +1,2 @@
 .direnv
+.mypy_cache

python/flake.nix

@@ -9,11 +9,16 @@
     flake-utils.lib.eachDefaultSystem (sys:
       let pkgs = nixpkgs.legacyPackages.${sys};
           python = pkgs.python310.withPackages (ps: with ps; [
-            matplotlib
             ipython
+            pylsp-mypy
           ]);
+          cfg = ./mypy-config.ini;
       in rec {
-        devShells.default = python;
+        packages.tychk-watch = pkgs.writeScriptBin "tychk" "echo 'running mypy on change...' ; ${pkgs.watchexec}/bin/watchexec -e py ${python}/bin/mypy --config ${cfg} ${./.}";
+        packages.tychk = pkgs.writeScriptBin "tychk" "${python}/bin/mypy ${./.} --config ${cfg}";
+        devShells.default = pkgs.mkShell {
+          packages = [ python ];
+        };
       }
     );
 }

python/mypy-config.ini

@@ -0,0 +1,5 @@
+[mypy]
+disallow_untyped_defs = True
+disallow_incomplete_defs = True
+check_untyped_defs = True
+