reif tpartition

[mvolkmann]

I hope I'm not asking too many questions and that they are good questions.

The following code gives the error "error(existence_error(procedure,is_dog/2),is_dog/2)" and I don't understand why. A is_dog rule with two arguments clearly exists. My assumption is that the first argument to tpartition should be a predicate that takes two arguments which are a value to be tested and a variable to be set to either true or false.

:- use_module(library(format)).
:- use_module(library(reif)).

dog(comet).
dog(maisey).
dog(oscar).
dog(ramsay).

writeln(X) :- write(X), nl.

is_dog(X, B) :- dog(X) -> B = true; B = false.

:- initialization((
  Beings = [mark, comet, tami, maisey, ramsay, oscar],
  tpartition(is_dog, Beings, Dogs, NonDogs),
  format("dogs include ~w~n", [Dogs]),
  format("non-dogs include ~w~n", [NonDogs])
)).

[mvolkmann]

I replaced the :- initialization(( line with run :- and deleted the two right parens at the end.
Then I ran this with scryerp -g run reif.pl and now it works fine.