Appendix F Restrictions and Limits
The ECL^{i}PS^{e} implementation tries to impose as few limits as possible.
The existing limits are:

The maximum arity of a predicate in ECL^{i}PS^{e} is 255
(this value can be queried with get_flag(max_predicate_arity, X)).
Note however that the arity of compound terms is unlimited.
 The maximum arity of external predicates in the current implementation
of ECL^{i}PS^{e} is 16.
 The stack and heap sizes have virtual memory limits which can be
changed using the g, l, s and p
command line options or the ec_set_option function in case of an
embedded ECL^{i}PS^{e}.
 When the occur check is disabled (the default)
it is possible (and sometimes useful) to create cyclic data structures.
For example, the unification of X and g(X) in
X = g(X)
will result in a cyclic structure
X = g(g(g(g(g(...)))))
Not all ECL^{i}PS^{e} builtin predicates handle cyclic terms gracefully.
Care must be taken with all predicates which traverse the whole term, e.g.,
copy_term/2,
term_hash/4,
writeq/2,
assert/1,
compile_term/1.
These will typically loop or overflow a stack when applied to cyclic terms.
Note however that, starting from version 5.6, cyclic terms are allowed in all
heap copying predicates (setval/2, bag_enter/2,
shelf_set/3, store_set/3, record/2, etc.).