Set keybinds for system yank/paste.

programs/kakoune.nix

@@ -16,6 +16,24 @@
         '';
       }
     ];
+    keyMappings = [
+        # Define usermode yank/copy and paste
+        {
+            key = "y";
+            mode = "user";
+            effect = "<a-|> wl-copy<ret>";
+        }
+        {
+            key = "p";
+            mode = "user";
+            effect = "<a-!> wl-paste<ret>;d"; # ;d at the end since newline inserted
+        }
+        {
+            key = "P";
+            mode = "user";
+            effect = "! wl-paste<ret>;d"; # ;d at the end since newline inserted
+        }
+    ];
   };
   extraConfig = ''
     eval %sh{kak-lsp --kakoune -s $kak_session}