You allude to the possibility of a name change at the end of the email. Progress on that is being tracked on this issue: https://github.com/ekmett/semigroupoids/issues/26. It seems like there is reasonable agreement that renaming Foldable1 (and several other classes from semigroupoids) would be good.

I'm in favor of moving this into base under the name Semifoldable (after it has been renamed in semigroupoids). Longer term, I think there's some interested stuff that could be done with fixing foldr1 and foldl1, which currently suffer a sad existence as partial functions.

On Thu, Jun 7, 2018 at 3:12 PM, Daniel Cartwright <chessai1996@gmail.com> wrote:

For those of you unfamiliar with 'Foldable1', it is a typeclass for nonempty foldable structures, that centres around Semigroup instead of Monoid.
I have made a differential on Phabricator for the change here: https://phabricator.haskell.org/D4812

Some discussion at the following links also:

https://ghc.haskell.org/trac/ghc/ticket/13573
https://www.reddit.com/r/haskell/comments/8p531d/ann_safefoldable_safe_wrappers_for_nullpartial/
https://github.com/ekmett/semigroupoids/issues/49

Note: foldl1 and foldr1 are currently typeclass methods of 'Foldable' and not 'Foldable1', and even though I think they should be, they probably (and shouldn't) be removed in this change, though I hope that eventually they can be moved to Foldable1.

Foldable1 is also unfortunately named due to the suffix '1' being connotated with the conventions surrounded Data.Functor.Classes (Show1, Eq1, etc.). If this naming is seen as sufficiently unfortunate/confusing because of that, then perhaps the name should be changed to something like 'SemiFoldable'. The name change would most likely have to be made in 'semigroupoids' first if that is the case.

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