let ctrlEqPlus = (base: string, shifted: string) =>
    (cm: EditorView, ev: KeyboardEvent) => 
            (ev.ctrlKey && (ev.key == '=' || ev.key == '+')) ?
                handleEvent(ev.shiftKey ? shifted : base) : false;

...
keymap.of([
    {any: ctrlEqPlus('ctrl-eq', 'ctrl-plus')}
])