Function parser

pub fn parser<'a, Y: 'a + 'static, X: 'a + 'static + Binder, E: Error<char> + 'a + 'static>(
    x: impl Parser<char, X, Error = E> + 'a + 'static + Clone,
    v: impl Parser<char, X::Var, Error = E> + 'a + 'static + Clone,
    y: impl Parser<char, Y, Error = E> + 'a + 'static + Clone,
    splice: impl Parser<char, GTerm<X, Y>, Error = E> + 'a + 'static + Clone,
) -> impl Parser<char, GTerm<X, Y>, Error = E> + 'a + 'static + Clone
where
    <X as Binder>::Var: 'a + 'static,
    GTerm<X, Y>: 'a + 'static,