Deprecate and Remove Data.Semigroup.Option and Data.Monoid.First/Last
Since the Semigroup-Monoid Proposal has landed, the data type
Data.Semigroup is now obsolete. I propose that it be marked deprecated in GHC 8.6 and removed in GHC 8.10.
--- EDIT ---
A proposal on the libraries mailing list for the removal of First and Last from Data.Monoid met with a positive response: https://mail.haskell.org/pipermail/libraries/2018-April/028712.html
I figured it would be best to track all of these on the same ticket. In a response to the aforementioned mailing list thread, Edward Kmett suggested that the timing for deprecation and removal be GHC 8.8 and GHC 8.10 respectively. This will make it possible to adhere to the three-release policy with ease.