Tests are very important, don't get me wrong. What I mean is that it's trivial to refactor large _trivial_ things with types -- ie, big restructures, renames, c

Tests are very important, don't get me wrong. What I mean is that it's trivial to refactor large _trivial_ things with types -- ie, big restructures, renames, clarifying things, etc -- where without it even small "large" things become dangerous and worksome.