Null object: Difference between revisions

=={{header|Erlang}}==

Erlang does not have an undefined value. As an alternative, many applications tend to pick a convention for return values and use that.

Example alternatives:

# Something like {ok, 3} or {err, no_more} on error.

# Don't ever allow an undefined return value, and throw an exception instead.

# Return an atom:

# undefined*

# undef

# null

# nil

# none

* Often used by records as an initial value and the stdlib module.

Atoms are erlang's user-defined constants that always evaluates to is itself. It is also equal to no other value else but itself.