Functors and monads are powerful design patterns used in Haskell. They give us two cool tricks for analyzing data. First, we can “preprocess” data after we’ve already trained a model. The model will be automatically updated to reflect the changes. Second, this whole process happens asymptotically faster than the standard method of preprocessing. In some cases, you can do it in constant time no matter how many data points you have! — Functors and monads for analyzing data