Hi,

Thanks for the hint -- it was sufficient to get me on the right
track.  Note however that instead of using the "compile" tag,
I had to use "ocamldep".  Also, the creation of the single-purpose
tag can be avoided by using "file:", as follows:

| After_rules ->
  dep ["ocamldep"; "file:foobar.ml"] ["data.txt"]

Best regards,
Dario Teixeira