What is the namespace in utop for definitions in .ml file listed in dune's (executable ...) rule?

Question

What is the namespace of the test0 definition in dune utop . environment, given the following ocaml code with dune build definition:

~/_ocaml_/n01$ cat bin/dune
(executable
 (public_name n01)
 (name main))

~/_ocaml_/n01$ cat bin/main.ml 
let test0 = "World!"
let () = print_endline  ("Hello " ^ test0)

When started the code produces expected result:

~/_ocaml_/n01$ dune build
~/_ocaml_/n01$ dune exec n01
Hello World!     

Answer 1

I believe that your issue is that you cannot access the test0 variable after launching dune utop ..

If I am not mistaken, your issue stems from the fact that the dune top <path> command loads libraries and not executable. Thus in your setup, the N01 module is not part of the utop environment. The idiomatic solution is to split your source files into a library and a small executable that only contains glue code.