Prelude folds now apply to any Foldable #50
Description
Related to #49, Prelude folds nowadays can fold on any Foldable so the entire sub-section of Monoids titled "Using monoids to fold data structures" which describes needing to import folds from Foldable in order to do so is out of date. Also, this sub-section on foldM uses the outdated datatype for folds too.