Developing multiple projects 'inline'?

[anchpop]

Desired Behavior

The docs give this example of a dune-project:

(lang dune 2.8)
(name cohttp)
; version field is optional
(version 1.0.0)

(generate_opam_files true)

(source (github mirage/ocaml-cohttp))
(license ISC)
(authors "Anil Madhavapeddy" "Rudi Grinberg")
(maintainers "[email protected]")

(package
 (name cohttp)
 (synopsis "An OCaml library for HTTP clients and servers")
 (description "A longer description")
 (depends
  (alcotest :with-test)
  (dune (> 1.5))
  (foo (and :dev (> 1.5) (< 2.0)))
  (uri (>= 1.9.0))
  (uri (< 2.0.0))
  (fieldslib (> v0.12))
  (fieldslib (< v0.13))))

(package
 (name cohttp-async)
 ; optional version override to allow single package point
 ; releases.
 (version 1.0.1)
 (synopsis "HTTP client and server for the Async library")
 (description "A _really_ long description")
 (depends
  (cohttp (>= 1.0.2))
  (conduit-async (>= 1.0.3))
  (async (>= v0.10.0))
  (async (< v0.12))))

I want to do a something similar: I want to have two packages, myproject and myproject-types (so people who don't want to pull in all the dependencies of myproject can still access the types), and I'd like their code to be kind of intermingled in the same folder structure, to keep the type definitions close to the code that uses those types. Naturally myproject will have to depend on myproject-types.

I can write something like the above and it works mostly fine. But there are two problems:

1. Installing dependencies: myproject-types gets added to myproject.opam, but myproject-types isn't on opam so installing the project dependencies with opam install --deps-only myproject.opam doesn't work (since it can't find myproject-types on opam).

2. Actually building: if we get all the other dependencies installed, dune build actually works fine since it'll build both myproject-types and myproject, but dune build -p myproject doesn't because dune complains of not being able to find myproject-types.

So my feature request is some kind of support for this use case, or advice for how to go about something like this :D

[bobot]

1. For installing dependencies for development you should use opam install --deps-only . . So that both opam files are taken into account and more importantly both packages will not be lookup for installation.

2. dune build -p myproject is specially designed for separate build and installation of the packages. So myproject-types must be installed before building myproject.

[rgrinberg]

I think @bobot's answers are adequate to address the issue and there's no bug to report. Moving to discussion.