Bulk types | such as lists, bags, sets, nite maps, and priority queues | are ubiquitous in programming. Yet many languages don't support them well, even though they have received a great deal of attention, especially from the database community. Haskell is currently among the culprits. This paper has two aims: to identify some of the technical di culties, and to attempt to address them using Haskell's constructor classes. The paper can also be read as a concrete proposal for new Haskell bulk type libraries. 1