Information for developers

If you want to update/modify GNU-Prolog without having to install each
working (intermediate) version simply use:

   % cd src
   % . ./SETVARS         (under sh/bash)
   % source ./CSHSETVARS (under csh/tcsh)

This updates the PATH variable and makes it possible to invoke gplc (and
gprolog) which resides in src/TopComp. gplc then detects that it is in a
development mode (use gplc -v to check this) and will use the libraries
residing in src/EnginePl, src/BipsPl, src/EngineFD, src/BipsFD, src/Linedit
(i.e the current development libraries and objects).

To test a new (pure) Prolog feature, define a file t.pl and t_c.c (maybe
empty) in BipsPl:

   % cd BipsPl
   % modify t.pl and t_c.c
   % make t
   % ./t to test

There is an entry in the Makefile that reconstruct t from t.pl and t_c.c.

Similarly, to test a new Prolog+FD feature, use t.pl, t_c.c and t_fd.fd in
BipsFD:

   % cd BipsFD
   % modify t.pl and/or t_c.c and/or t_fd.fd
   % make t
   % ./t (to test)

There is an entry in the Makefile that reconstruct t from t.pl, t_c.c and
t_fd.fd. 
