dune format-dune-file on dune-project is suboptimal

[avsm]

The results of running dune format-dune-file < dune-project ends up looking a bit terrible:

(lang dune 1.10)

(name github)

(generate_opam_files true)

(license MIT)

(maintainers "Anil Madhavapeddy <[email protected]>")

(authors "Anil Madhavapeddy" "David Sheets" "Andy Ray" "Jeff Hammerbacher"
  "Thomas Gazagnaire" "Rudi Grinberg" "Qi Li" "Jeremy Yallop" "Dave Tucker")

(source
 (github mirage/ocaml-github))

(documentation "https://mirage.github.io/ocaml-github/")

(package
 (name github)
 (tags
  (org:mirage org:xapi-project git))
 (depends
  (ocaml
   (>= 4.03.0))
  (dune
   (>= 1.10))
  (uri
   (>= 1.9.0))
  (cohttp
   (>= 0.99.0))
  (cohttp-lwt
   (>= 0.99))
  (lwt
   (>= 2.4.4))
  (atdgen
   (>= 2.0.0))
  (yojson
   (>= 1.6.0))
  stringext)
 (synopsis "GitHub APIv3 OCaml library")
 (description
   "This library provides an OCaml interface to the\n[GitHub APIv3](https://developer.github.com/v3/) (JSON).\n\nIt is compatible with [MirageOS](https://mirage.io) and also compiles to pure\nJavaScript via [js_of_ocaml](http://ocsigen.org/js_of_ocaml)."))

(package
 (name github-jsoo)
 (tags
  (org:mirage org:xapi-project git))
 (depends
  (ocaml
   (>= 4.03.0))
  (dune
   (>= 1.10))
  (github
   (= :version))
  (cohttp
   (>= 0.99.0))
  (cohttp-lwt-jsoo
   (>= 0.99.0))
  (js_of_ocaml-lwt
   (>= 3.4.0)))
 (synopsis "GitHub APIv3 JavaScript library")
 (description
   "This library provides an OCaml interface to the [GitHub APIv3](https://developer.github.com/v3/)\n(JSON). This library installs the JavaScript version, which uses [js_of_ocaml](http://ocsigen.org/js_of_ocaml)."))

vs the original which was much more compact:

(lang dune 1.10)
(name github)

(generate_opam_files true)

(license MIT)
(maintainers "Anil Madhavapeddy <[email protected]>")
(authors "Anil Madhavapeddy" "David Sheets" "Andy Ray"
  "Jeff Hammerbacher" "Thomas Gazagnaire" "Rudi Grinberg"
  "Qi Li" "Jeremy Yallop" "Dave Tucker")
(source (github mirage/ocaml-github))
(documentation "https://mirage.github.io/ocaml-github/")

(package
 (name github)
 (tags (org:mirage org:xapi-project git))
 (depends
  (ocaml (>= 4.03.0))
  (dune (>= 1.10))
  (uri (>= 1.9.0))
  (cohttp (>= 0.99.0))
  (cohttp-lwt (>= 0.99))
  (lwt (>= 2.4.4))
  (atdgen (>= 2.0.0))
  (yojson (>= 1.6.0))
  stringext)
 (synopsis "GitHub APIv3 OCaml library")
 (description "This library provides an OCaml interface to the
[GitHub APIv3](https://developer.github.com/v3/) (JSON).

It is compatible with [MirageOS](https://mirage.io) and also compiles to pure
JavaScript via [js_of_ocaml](http://ocsigen.org/js_of_ocaml)."))

Some things that might help are:

• putting each dependency clause on a single line
• wrapping long strings like description

[emillon]

Yes, I agree that it's not great for now (fortunately, it's not set up by formatting rules). Some rules we can adapt:

• this should be formatted as fields in a giant (dune_project) stanza - that would remove all the newlines.
• lists of strings in maintainers and authors should go one per line
• each package in (depends) should go on a single line

It would be nice if this was not a second ad-hoc formatter, but we'll see what we can do.

[nojb]

Should have been fixed by #3928