Add some primops to lib

nixos/modules/config/shells-environment.nix

@@ -31,9 +31,9 @@ in
             res = (head defs').value;
           in
           if isList res then concatLists (getValues defs')
-          else if builtins.lessThan 1 (length defs') then
+          else if lessThan 1 (length defs') then
             throw "The option `${showOption loc}' is defined multiple times, in ${showFiles (getFiles defs)}."
-          else if !builtins.isString res then
+          else if !isString res then
             throw "The option `${showOption loc}' does not have a string value, in ${showFiles (getFiles defs)}."
           else res;
       });