How can I get the list of active and inactive users without using any plugin?
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"lambda function who shall not be named" is especially alarming since in the same breath you deigned to speak the name of the eval function.
Except that one has actually been mentioned here before so...
To echo what others have said (in case anyone else comes across this thread later as well), there are many functions that are used internally by software developers at Appian that are not intended to be used within Designer expressions by low-code developers. These functions are undocumented, have not been tested within Designer expressions, and their behavior can change at any time, in any release.
I strongly suggest that you do not use them, even if just during an investigation or testing, because the results can be unexpected. If you believe you have a need for one of these functions, please create a support case for a feature request and provide additional context for what your use case is.