Archived tweet #11057 from the @leastfixedpoint Twitter Archive

@prathyvsh Isn't it neat! I just read that page yesterday. Those G(x)/M(x) functors are cool; e.g. after an exception, if x = "is this piece of mutable state damaged?" then M(x) is "must I discard and rebuild this piece of state?" and N(M(x)) is "can I keep it?"