Some more recent ones of note... 0. When I learned how to model systems in TLA+ 1. When I figured out how to structure programs using monad transformers... so

Some more recent ones of note... 0. When I learned how to model systems in TLA+ 1. When I figured out how to structure programs using monad transformers... sort of the moment where I started reasoning algebraically about programs on my own 2. When I learned how to specify propositions in types and verify my designs and programs