thread_barrier_test_helper_1.m:167: In clause for predicate
thread_barrier_test_helper_1.m:167:   `write_out_thread_messages'/4:
thread_barrier_test_helper_1.m:167:   warning: variable `IO' occurs only once
thread_barrier_test_helper_1.m:167:   in this scope.
thread_barrier_test_helper_1.m:167: In clause for predicate
thread_barrier_test_helper_1.m:167:   `write_out_thread_messages'/4:
thread_barrier_test_helper_1.m:167:   error: undefined predicate `-'/2.
thread_barrier_test_helper_1.m:167:   (There is a *function* with that name,
thread_barrier_test_helper_1.m:167:   however.
thread_barrier_test_helper_1.m:167:   Perhaps you forgot to add ` = ...'?)
thread_barrier_test_helper_1.m:167: In clause for predicate
thread_barrier_test_helper_1.m:167:   `write_out_thread_messages'/4:
thread_barrier_test_helper_1.m:167:   in argument 1 of call to predicate `-'/2:
thread_barrier_test_helper_1.m:167:   error: undefined symbol `list'/0.
thread_barrier_test_helper_1.m:167: In clause for predicate
thread_barrier_test_helper_1.m:167:   `write_out_thread_messages'/4:
thread_barrier_test_helper_1.m:167:   in argument 2 of call to predicate `-'/2:
thread_barrier_test_helper_1.m:167:   in argument 3 of functor `foldr/3':
thread_barrier_test_helper_1.m:167:   error: invalid use of `!' state variable
thread_barrier_test_helper_1.m:167:   operator.
For more information, recompile with `-E'.