dune-ocaml : No implementations provided for the following modules:

Learning
1

Hello All,

I tried to compile an OCaml code with Dune but got the following error: Error: No implementations provided for the following modules:
CallccBp referenced from bin/.CallccTest.eobjs/native/dune__exe__CallccTest.cmx

by executing the command : $ dune build

My project hierarchy is as follows:

callcc/
bin/
callccTest.ml
dune
[
(executable
(name callccTest)
(libraries CallccBp))
]
lib/
CallccBp.mli
dune
[
(library
(name CallccBp)
(modules_without_implementation CallccBp))
]
test/
callccTest.ml
dune [
(test
(name callccTest))
]

callcc.opam
dune-project

How can I solve this problem?

Thank you.

2

What is the content of callccBp.mli? Does it define any exception?

Cheers,
Nicolas

3

callccBp.mli
type 'a cont
val callcc: ('a cont → 'a) → 'a
val throw: 'a cont → 'a → 'b

callccTest.ml
open callccBp
let now () =
let s = ref None in
callcc (fun k → s := Some k);
s

let past_travel_to date =
match !date with
| None → assert false
| Some date → throw date ()

let cake = ref Cake let eat () = assert (!cake = Cake);
Printf.printf “I am eating the cake! Miamee!\n”;
cake := `NoMoreCake

let _ =
let t = now () in
Printf.printf “I am in front of the cake\n.”;
eat ();
past_travel_to t

4

The module CallccBp declares values callcc and throw, so it needs an implementation: you cannot use modules_without_implementation for such modules. You must provide an implementation.

Cheers,
Nicolas

5

Without the deposit
(modules_without_implementation callccBp)

I have the following error: File “lib/dune”, line 1, characters 0-26:
1 | (library
2 | (name CallccBp))
Error: Some modules don’t have an implementation.
You need to add the following field to this stanza:

(modules_without_implementation callccBp)

6

You need to write down a callccBp.ml file

type 'a cont = ...
let callcc = ...
let throw = ...

What is the general context? It is a bit surprising that you ended up writing a library without knowing what are mli fles.

7

When I first tried the program it gave me the signature error and I didn’t know there was another solution.

With :
type 'a cont
let callcc = ('a cont → 'a) → 'a
let throw = 'a cont → 'a → 'b

I have error :
File “bin/CallCCTest.ml”, line 2, characters 14-15:
2 | let callcc = ('a cont → 'a) → 'a
^
Error: Syntax error: operator expected.

8

This is not valid OCaml code: a type is not an implementation.

At this point, it is probably better to try to take some distance and take the time to contextualize what you are trying to do.

9

Thank you for your help.
I tried to transfer the code from Ocaml to Coq, I found the coq-of-ocaml tool. for this the code must be compiled with dune.