GridFS is a convention for storing large files in MongoDB.
Most drivers from the MongoDB team include GridFS support. The Haskell driver does not.
This driver was initially provided as an attachment by Martin Norbäck Olivers at https://jira.mongodb.org/browse/HASKELL-14. The maintainers at MongoDB haven't acted on it or provided their own GridFS implementation, so I'm packaging it as a standalone library and putting it on Hackage to make it easier to use.