# $/0, $/1 bug or misunderstanding

**URL:** <https://swi-prolog.discourse.group/t/0-1-bug-or-misunderstanding/7265>\
**Category:** General\
**Created:** [February 27, 2024, 5:50pm UTC](https://swi-prolog.discourse.group/t/0-1-bug-or-misunderstanding/7265 "2024-02-27T17:50:46Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![z5h](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/z5h/32/5445_2.png) [@z5h](https://swi-prolog.discourse.group/u/z5h)\
**Post date:** [February 27, 2024, 5:50pm UTC](https://swi-prolog.discourse.group/t/0-1-bug-or-misunderstanding/7265/1 "2024-02-27T17:50:46Z")

</div>

This makes sense to me

```prolog
?- $(member(X,[1,2,3])).
ERROR: Goal member(1,[1,2,3]) succeeded with a choice point

```

This seems like the error is that we don’t know what the error is. Is this not the way to use `$/0`?

```prolog
?- $, member(X,[1,2,3]).
ERROR: Unknown error term: determinism_error(lists:member_/3,det,nondet,guard_in_caller)

```