error

Error: This expression should not be a function, the expected type is
Js.js_string Js.t

fail.ml

Elem (DOM.make ~tag:`input ~elem_spec:
                           ([("type", Js.string "checkbox");
                             ("onClick", (fun _ -> swap initial_state (fun state -> set_tab !state All)));
                             ("checked", Js.string (if task.completed then "checked" else ""));
                             ("className", Js.string "toggle")]
                            >>> object%js end)
                           [])