Problem with pretty-printing of lists in toplevel when opening List module

[tofgarion]

I am using OCaml 4.09.0 from OPAM and I have just noticed something peculiar using the toplevel.

When evaluating 1 :: 2 :: [], the list is pretty-printed as usual:

# 1 :: 2 :: 3 :: [] ;;
- : int list = [1; 2; 3]

If I open first the List module, then the printing is different:

# let open List in 1 :: 2 :: 3 :: [] ;;
- : int List.t = (::) (1, [2; 3])

The list is now typed with the type t used in the List module signature
and the list representation is different.

Florian Angeletti has just posted an explanation on caml-list (see https://inbox.ocaml.org/caml-list/87v9ntdpx4.fsf@port-garion.isae.fr/T/#m81832d8a041da3a1306426ecd78944e95d47fd54) and a PR with a solution, see #9336.

Best,

Christophe

[mshinwell]

The discussion on #9336 can supercede this issue.