# Learning persistency for complex terms

**URL:** <https://swi-prolog.discourse.group/t/learning-persistency-for-complex-terms/1500>\
**Category:** Help!\
**Created:** [November 13, 2019, 6:03am UTC](https://swi-prolog.discourse.group/t/learning-persistency-for-complex-terms/1500 "2019-11-13T06:03:13Z")\
**Posts on this page:** 1\
**Showing post:** 6

<div class="post-metadata">

**Author:** ![EricGT](https://avatars.discourse-cdn.com/v4/letter/e/f1d935/32.png) [@EricGT](https://swi-prolog.discourse.group/u/EricGT)\
**Post date:** [November 13, 2019, 10:05pm UTC](https://swi-prolog.discourse.group/t/learning-persistency-for-complex-terms/1500/6 "2019-11-13T22:05:45Z")

</div>

> [@Boris](#):
>
> You then have to read through it and look at the table in the [docs for `must_be/2`](https://www.swi-prolog.org/pldoc/doc_for?object=must_be/2).

That is not the full list. To see the full list one needs to look at the code for [has\_type/2](https://github.com/SWI-Prolog/swipl-devel/blob/8640fd71eb55dd13c1669bb7d5a224d6fb17903a/library/error.pl#L333)

* * *

To OP, you may find this of interest as it relates to library persistence.

[Solving two consecutive dependent goals from command line](https://swi-prolog.discourse.group/t/solving-two-consecutive-dependent-goals-from-command-line/1270)

---

_[View the full topic](https://swi-prolog.discourse.group/t/learning-persistency-for-complex-terms/1500)._