expectfalse

Expectfalse is a command used in the programming language Prolog. It is a built-in predicate that is used to test whether a given goal fails. The predicate takes a single argument, which is the goal to be tested. If the goal succeeds, expectfalse fails, and if the goal fails, expectfalse succeeds. This can be useful in various scenarios, such as testing the correctness of a program or ensuring that certain conditions are not met. For example, if you want to ensure that a certain rule does not hold, you can use expectfalse to test for its failure. The predicate is part of the standard Prolog library and is available in most Prolog implementations. It is important to note that expectfalse should be used with caution, as it can lead to unexpected behavior if not used correctly. For instance, if the goal being tested has side effects, these side effects will still occur even if the goal fails. Therefore, it is recommended to use expectfalse only for testing purposes and not in production code.