#9 get the list of annotations

[Jomi Fred Hubner]

the problem is how to obtain the list of all annotations of a predicate.

currently, we can write

X = p[a,b];
...
p[H|T] = X;
L = [H|T];

to get the annotations of X in L.

besides to verbose, it only works if X has at least one annotation. it X's annotations are empty, the unification will fail. A solution is to use a rule like

get_annots(X[], []).
get_annots(X[H|T], [H|T]).

and the program is

X = p[a,b];
...
?get_annots(X,L);

Another proposal:

X = p[a,b];
...
p@L = X;

where @ pre-fix the annotations (this symbol already means annotations in plans)

for compatibility reasons, p[....] and p@[....] should both work.

Maybe it doesn't worst to change the syntax for some rare use (and that some rules -- or a new internal action -- can solve).

[Jomi Fred Hubner]

another option to obtain the annotations of a literal is the operator =..

X = p[a,b];
...
X =.. [_,_,L];
...