This is a good introduction, and a very useful abstraction. At Morgan Stanley we have built a PL/compiler and tools around a method of logging like this -- log

This is a good introduction, and a very useful abstraction. At Morgan Stanley we have built a PL/compiler and tools around a method of logging like this -- logging algebraic data types and live querying out of them with Haskell-like comprehensions/pattern-matching/etc: https://github.com/Morgan-Stanley/hobbes https://github.com/Morgan-Stanley/hobbes