@hackage enummapset-th0.5.1.0

This package wraps IntSet and IntMap from containers, and provides fast sets and maps keyed on any data type with a well-behaved Enum instance. Useful for derived Enums, newtype'd Ints, or any data type that can be packed into an Int: just implement fromEnum and toEnum.

The boilerplate is generated using Template Haskell, so unlike enummapset it's easier to maintain and keep up-to-date with containers. On the downside, it's less portable.