A FFI for evaluable functions

The implementation to allow native libraries to register
new evaluable functions is the same as how predicates
are consulted. Take these two files:
$ cat > foo.p
test :- hello.
$ cat > bar.p
hello :- write('hello'), nl.
If I consult foo.p before bar.p there is a forward reference.
But if I ultimately consult bar.p the forward reference is
resolved. How does a Prolog system do that?
$ target/release/scryer-prolog
?- ['foo.p'].
    true.
?- test.
    error(existence_error(procedure,hello/0),hello/0).
?- ['bar.p'].
    true.
?- test.
hello
    true.
Now enhance is/2, etc... so that it uses the same resultion
meachanism, but only for the evaluable function namespace,
and provide a FFI where one can register evaluable functions,
in the evaluable function namespace, eh voila you are done,
makeing your Prolog extensible. Allowing to register evaluable
functions like gdc/2, popcount/1, etc.. outside of the core.
Mild Shock schrieb:

The new multilingual strings are also an exercise in
Novacore. There were a few issues that needed novel
Prolog solutions, to make a Novacore solution.
 One problem was I didn't want to use library(format)
and format/3 to format multilingual strings when
generating error messages. This addresses more
 the later multilingual strings processing than the
multilingual strings store itself. So how resolve this
paradox? Here is my take, a mini format/3 boostraped
 from the Dogelog Player specific atom_split/3:
 % sys_inter_polate(+Stream, +Atom, +List)
sys_inter_polate(Stream, Template, Args) :-
    atom_split(Template, '~', [Head|Tail]),
    put_atom(Stream, Head),
    sys_zipper_output(Args, Tail, Stream).
 % sys_zipper_output(+List, +List, +Stream)
sys_zipper_output([Arg|Args], [Head|Tail], Stream) :-
    writeq(Stream, Arg),
    put_atom(Stream, Head),
    sys_zipper_output(Args, Tail, Stream).
sys_zipper_output([], [], _).
 It only understands format specifier '~', but is sufficient:
 /* German Text */
strings('syntax_error.singleton_var', de, 'Alleinstehende Variable(n) ~, anonyme Variable(n) (_) benutzen.').
 /* English and Fallback Text */
strings('syntax_error.singleton_var', '', 'Singleton variable(s) ~, use anonymous variable(s) (_).').
 LoL