The *(term) for a dichotomy or a division in a space of possibilities. There are many dualities in programming, often surrounded by fallacies.

In the _(programming language) mode of thinking about programming, we have _(pure) vs. _(side effect)ing expressions, languages, and such, also expressed as the distinguishment between _(referential transparency and state).

There is also _(low-level) vs. _(high-level), for those who are obsessed with implementation as a spectrum.

From _(category theory) or abstract math/logic in general, we have _(induction and co-induction) or _(algebra and coalgebra). This relates also to being _(well-founded) vs. _(non-well-founded).

A separate duality in category theory is _(initiality and finality).
