Row-types is a library of open records and variants for Haskell using closed type families and type literals (among other things...). See examples/Examples.lhs for a literate Haskell file that functions as an overview of how this library can be used, and check out the website for further examples.
Available on Hackage.
This work is a branch from CTRex [1,2] with other inspiration from data-diverse [3]. My thanks to the authors and contributors of those libraries!
[1] https://wiki.haskell.org/CTRex
[2] https://hackage.haskell.org/package/CTRex/docs/Data-OpenRecords.html
[3] https://hackage.haskell.org/package/data-diverse