This package would have to depend on the availability of all 5 Prolog systems and, in perspective also of OCaml, Java, Mathematica, ... We need another idea.
Why does this interfaces-package depend on those systems - isn't it the other way round (if one intends to use PPL)? But ...
You may need the language X development environment installed for installing the X-PPL interface. If you package the interfaces X-PPL, Y-PPL and Z-PPL together you may end up with the situation where the user is only interested in X-PPL but is required to have also Y installed in order to install the single interfaces package. This is something we want to avoid right from the start.
I'm sorry, but I still don't get the point - why would I need the "language X development environment" to install a library? IMHO
- it might be required to build it -> build-depend or - the library alone is of course not useful -> Suggests: ...
Would you mind giving an example - I just don't understand ...
Sorry, Michael