I finally found http://ocaml.org/learn/tutorials/ocamlbuild/Using_internal_libraries.html (which didn't come up earlier because I was searching for "subdirectory"); following that I added a myocamlbuild file:

 $ cat myocamlbuild.ml 
open Ocamlbuild_plugin

let () =
  dispatch begin function
  | After_rules ->
     ocaml_lib "plugins/puz/Puz_plugin";
  | _ -> ()
  end

but then attempting to add to the _tags file:

<file.*>: use_puz_plugin

gave me the following:

Warning: the tag "use_puz_plugin" is not used in any flag or dependency declaration, so it will have no effect; it may be a typo. Otherwise you can use `mark_tag_used` in your myocamlbuild.ml to disable this warning.
+ ocamlfind ocamlc -c -g -thread -package core_kernel -I plugins/puz -o file.cmo file.ml
File "file.ml", line 5, characters 2-17:
Error: Unbound module Puz_plugin


Feedback on the tutorial: It would be useful to have a complete repository corresponding to each of the examples, that could be checked out and played with.

martin



On Mon, Sep 21, 2015 at 11:23 PM, Martin DeMello <martindemello@gmail.com> wrote:
If I have my project set up like this:

.
├── file.ml
├── plugins
│   └── puz
│       ├── puz_bin.ml
│       ├── puz_match.ml
│       ├── puz.ml
│       ├── puz_plugin.mllib
│       ├── puz_types.ml
│       └── puz_utils.ml
└── _tags

$ cat plugins/puz/puz_plugin.mllib 
Puz Puz_bin Puz_match

This works:

$ ocamlbuild -use-ocamlfind plugins/puz/puz_plugin.cmxa
Finished, 22 targets (3 cached) in 00:00:03.

My _tags file:
------------------------------------------------
$ cat _tags 
true: thread,debug
true: package(core_kernel)

"plugins/puz": include

<gui.*>: package(labltk)
<**/puz.*>: package(unix), package(str), package(core_kernel), package(bitstring), package(mikmatch_pcre)
<**/*_bin.*>: package(bitstring.syntax), syntax(bitstring)
<**/*_match.*>: package(mikmatch_pcre), syntax(camlp4o)
------------------------------------------------

But I can't figure out how to use this library in my main program. This is a minimal example of what I'm trying to do, not working of course:

$ cat file.ml 
open Core_kernel.Std

let read fname =
  let data = In_channel.read_all fname in
  Puz_plugin.read data

$ ocamlbuild -use-ocamlfind file.native
+ ocamlfind ocamlc -c -g -thread -package core_kernel -I plugins/puz -o file.cmo file.ml
File "file.ml", line 5, characters 2-17:
Error: Unbound module Puz_plugin

martin