Unbound module and module type in dune build

Learning
,
1

Hi. Wanted to try out dune today with a basic project, but couldn’t get it working. Here is my project structure

test/
├── dune-project
├── test.opam
├── lib/
│   ├── dune
│   ├── greeter.ml
│   └── greeter.mli
├── bin/
│   ├── dune
│   └── main.ml

while doing dune build I got 2 errors.

 test  ᐅ  dune build            
File "lib/greeter.ml", line 1, characters 17-28:
Error: Unbound module type Greeter_sig
File "bin/main.ml", line 2, characters 2-15:
Error: Unbound module Greeter

Files in the lib folder

greeter.ml

module Greeter : Greeter_sig = struct
  let greet name =
    Printf.printf "Hello, %s!\n" name
end

greeter.mli

module type Greeter_sig = sig
  val greet : string -> unit
end

dune (the one in the lib directory)

(library
 (name test)
 (public_name test)
 (modules greeter) )

Now dune-project

(lang dune 2.8)

(name test)

and finally bin directory

main.ml

let () =
  Greeter.greet "World"

dune

(executable
 (name main)
 (libraries test))

Any ideas on how to fix it?

2

OCaml source files are automatically modules, so you don’t need to declare nested modules with the module and module type keywords. Also, I strongly recommend that you match each directory’s name with the name of its main module. This will greatly reduce the number of different concepts you have to worry about:

bin/
  bin.ml
  dune
greeter/
  dune
  greeter.ml
  greeter.mli

And the dune files:

; bin/dune
(executable
  (name bin)
  (libraries greeter))

; greeter/dune
(library
  (name greeter))
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