The term ‘nil’ refers to the absence of value, but we often imbue it with much more meaning than just that. Today, hosts Joël and Stephanie discuss the various ways we tend to project extra semantics onto nil and the implications of this before unpacking potential alternatives and trade-offs.

Joël and Stephanie highlight some of the key ways programmers project additional meaning onto nil (and why), like when it’s used to create a guest session, and how this can lead to bugs, confusion, and poor user experiences. They discuss solutions to this problem, like introducing objects for improved readability, before taking a closer look at the implications of excessive guard clauses in code.

Our hosts also explore the three-state Boolean problem, illustrating the pitfalls of using nullable Booleans, and why you should use default values in your database. Joël then shares insights from the Elm community and how it encourages rigorous checks and structured data modeling to manage nil values effectively.

They advocate for using nil only to represent truly optional data, cautioning against overloading nil with additional meanings that can compromise code clarity and reliability. Joël also shares a fun example of modeling a card deck, explaining why you might be tempted to add extra semantics onto nil, and why the joker always inevitably ends up causing chaos!


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