This package uses closed type families and type literals to implement open
records and variants. The core is based off of the CTRex package, but it
also includes polymorphic variants and a number of additional
functions. That said, it is not a proper superset of CTRex as it
specifically forbids records from having more than one element of the same
label.

Homepage:
http://hackage.haskell.org/package/row-types
