Depends on 2 packages(full list with versions):
Used by 5 packages in nightly-2020-11-16(full list with versions):

Monad classes using type families, with instances for various monad transformers, inspired by the paper /Functional Programming with Overloading and Higher-Order Polymorphism/, by Mark P Jones, in Advanced School of Functional Programming, 1995 (http://web.cecs.pdx.edu/~mpj/pubs/springschool.html).

This package is almost a compatible replacement for the mtl-tf package.