Illegal vs. Unwanted States

April 28, 2026 Illegal vs Unwanted States Keep Unwanted States Representable An illegal state is a state we never want our system to be in. An unwanted state is a state we don't want to stay in. Many states that we wish were illegal are actually unwanted. Considering a calendaring software which stores calendar events as {user: {events: [event]}}, where each event has a start and end time. This allows one person to attend two events at the same time. We might consider this illegal and replace the data type with {user: {time: optional event}} which makes this impossible. However, a scheduling conflict isn't illegal, only unwanted! It is possible for a person to sign up for two overlapping events.

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Excerpt limited to ~120 words for fair-use compliance. The full article is at Buttondown.