more SWI stuff.

pl/utils.yap

@@ -719,3 +719,21 @@ subsumes_term(A,B) :-
 	\+ \+ terms:subsumes(A,B).
 
 
+%%	file_name_on_path(+File:atom, -OnPath) is det.
+%
+%	True if OnPath a description of File   based  on the file search
+%	path. This performs the inverse of absolute_file_name/3.
+
+file_name_on_path(Path, ShortId) :-
+	(   file_alias_path(Alias, Dir),
+	    atom_concat(Dir, Local, Path)
+	->  (   Alias == '.'
+	    ->  ShortId = Local
+	    ;   file_name_extension(Base, pl, Local)
+	    ->  ShortId =.. [Alias, Base]
+	    ;   ShortId =.. [Alias, Local]
+	    )
+	;   ShortId = Path
+	).
+
+