computed signal does not recalculate when depending signal uses equality function about angular HOT 2 CLOSED

Your example is attempting to update list mutably, but the custom equality function doesn't handle mutable updates.

this.list.update((list) => {
      list.push('a');
      return list;
    });

This call to update returns the same instance of the array (after pushing a new item). This will call the custom equality function with the same instance of the array as arr1 and arr2. Since the implementation compares arr1.length === arr2.length it will return true, which makes list assume nothing has changed (and not propagate a notification).

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@alxhub thanks for your reply and explanation, which makes totally sense (embarrassing I didn't see that myself).
As a consequence, we must always provide a new instance for set() and update() for signals. After realising the issue, it is clear to me. Nevertheless, I think it would be helpful to add this to the Signal guide - it should be especially mentioned in the section Signal equality functions which was misleading me (I see that the example is to show that two different instances with the same content should be considered equal).

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