Regarding the example at the end of the post, how does it even make sense to allow an anonymous arrow function be a "paramater name" (yes!) of another anonymous function? I guess the empty object becomes a destructuring parameter that doesn't do anything but the function is confusing:

    (
      (
        {},
        {},
        ({},{})=>({},{})
      )=>
      (({},{})=>({},{}),{},{})
    )({},{})

I can rewrite that to be more clear:

    //(({},{})=>({},{}),{},{}) evaluates to {}
    //({},{}) evaluates to {}
    let fn = ({}, {}, ({},{})=>{}) => {};
    fn({},{});

This is just a syntax error, I guess (hope)?