Is there a good reason why it does not have: A good question. See - (2017) https://gitlab.haskell.org/ghc/ghc/-/issues/13573 - (2017) https://www.reddit.com/r/haskell/comments/6d0vgt/could_we_have_foldable1_and... - (2019) https://mail.haskell.org/pipermail/libraries/2019-November/030059.html - (2020) https://mail.haskell.org/pipermail/libraries/2020-December/031003.html - (2021) https://twitter.com/kmett/status/1363774888603914242 For recent bits and bobs of the possible answers. - Oleg On 14.5.2021 22.54, coot@coot.me wrote:
Base has: * foldMap :: (Foldable t, Monoid a) => (x -> a) -> t x -> a * foldr1 :: (Foldable t) => (a -> a -> a) -> t x -> a Is there a good reason why it does not have: ``` foldMap1 :: (Foldable t, Semigroup a, Functor f) => (a -> a) -> t x -> a foldMap1 = fodlr1 (<>) . fmap f ``` Like `foldr1` it is partial for any foldable that can be empty.
Best regards, Marcin Szamotulski
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