Hi all, I tried to contact John Dorsey who is the sole maintainer of OneTuple [1], but the stated email address (haskell@colquitt.org) bounces back. The last version of OneTuple was uploaded "by JohnDorsey at Tue Mar 24 17:35:51 UTC 2009" - 9 years ago. OneTuple was working great so far, but GHC-8.4.1 / base-4.11 introduced breaking change, which affects OneTuple too: Semigroup is now a superclass of Monoid. Therefore none of OneTuple versions is GHC-8.4.1/base-4.11 compatible. I'm a Hackage Trustee [1] and also a user of OneTuple package (though not direct - it's in the transitive closure of Chart + diagrams), so I'd like to see GHC-8.4 compatible OneTuple version soon. The required changes are very small, see https://github.com/phadej/OneTuple/pull/1 or more precisely this exact commit: https://github.com/phadej/OneTuple/pull/1/commits/1dbc4d3186f707034953e13199... I'd like to become (co-)maintainer of OneTuple. I have no other plans than to keep it compiling with recent versions of GHC. Maybe I'll add NFData (from `deepseq`) instance though. Best Regards, Oleg Grenrus [1]: https://hackage.haskell.org/package/OneTuple