This example illustrates the use of
augment the built-in predicate
expand_term/2, which works
as a filter on the input to compile and consult. The code
below will allow the declaration `:- wait f/3' as an alias
for `:- block f(-,?,?)'. Wait declarations were used in
previous versions of SICStus Prolog.
multifile declaration, which prevents this
user:term_expansion/[2,4] clause from erasing any other
clauses for the same predicate that might have been
:- op(1150, fx, [wait]). :- multifile user:term_expansion/2. user:term_expansion((:- wait F/N), (:- block Head)) :- functor(Head, F, N), wb_args(N, Head). wb_args(0, _Head). wb_args(1, Head) :- arg(1, Head, -). wb_args(N, Head) :- N>1, arg(N, Head, ?), N1 is N-1, wb_args(N1, Head).