State

Computer programming is much more difficult than it should be. It's much less elegant than it should be. Programs often resemble logical Rube Goldberg machines, or corporate income tax forms.

This complexity is caused by our inability to properly manage "state", or information that changes over time. Procedural programming, object oriented programming, domain driven design, immutable data structures, and monads are all attempts to better manage state, and none of them are good enough.

The more recent functional reactive technologies are a step in the right direction. React is good, and MobX, Javelin, and Matrix are better. Serious programming can be as easy as spreadsheets. We can have full referential transparency, and we can refactor without fear.