You stand in good company:

Let us change our traditional attitude to the construction of programs. Instead of imagining that our main task is to instruct a computer what to do, let us concentrate rather on explaining to human beings what we want a computer to do.

Donald Knuth, 1992

I also like this one:
module String = struct include Stdlib.String module Map = Map.Make(Stdlib.String) end

Quite an effort indeed, but with a high degree of parallelizability.

That looks fine. I'm among those who don't use polymorphic variants unless there's a strong case for such as ocaml.org/docs/error-h...

Indeed it does. It's >>= fun, which is the same as let*. Custom binder gives you a free (and hidden) eta.

Yes, it is. But I find it particularly disturbing in that case. We hear >>= and let* are the same. Not in that respect.

1: f L gives I. n is a T with holes labelled x or y. 2: chop Is gives H2 hole set. 3&4: chop 2s gives H3 and H4 hole sets. {x} = H2 ∩ H3, {y} = H2 ∩ H4. Something like that? Haven't written the code. Can you solve that as polynomial coefficients from points?

Isn't it Barron and Strachey product? That's far from trivial.