I think Michael Snoyman did a good job of starting that conversation with his IsSequence class in mono-traversable. I don't agree with a lot of the specific design decisions he's made, but I think we should definitely think about previous experience in that space.

Personally, I prefer an MPTC-based interface for the monomorphic stuff. This is mostly a matter of taste, of course. One important idea, of course, is that of a free monoid:

type family Elem xs

class e ~ Elem c => MonoFoldable e c where

mfoldMap :: Monoid m => (e -> m) -> c -> m

class (MonoFoldable e c, Monoid c) => MonoSequence e c where

mSingleton :: e -> c

-- All other methods can be optional

class (forall e. Monoid (t e)) => Monoid1 t

instance (forall e. Monoid (t e)) => Monoid1 t

class (Traversable t, Monoid1 t) => Sequence t where

singleton :: e -> t e

-- All other methods can be optional

On Thu, Sep 12, 2019, 10:42 AM Andreas Abel <andreas.abel@ifi.lmu.de> wrote:

I think this proposal was be stronger if it would lay out the bigger
picture, i.e., directions towards a unified interface to sequence-like
collections.

-1 in its current form.

On 2019-09-11 16:32, Helmut Schmidt wrote:
> Taylor,
>
> Is it really necessary for you to be so rude? I can assure you that my
> proposal has been made in the same good faith as your proposal which
> inspired mine.
>
> Besides that unnecessary snark you do make an excellent point regarding
> the poor discoverability of the list constructor which I imagine must
> cause a lot of confusion among newcomers.Thank you for keeping an open mind!
>
>
>
> Am Mi., 11. Sept. 2019 um 11:21 Uhr schrieb Taylor Fausak
> <taylor@fausak.me <mailto:taylor@fausak.me>>:
>
> I suspect this proposal was not made in good faith. I feel like it
> was meant to make fun of my list singleton proposal.
>
> In spite of that, I am in favor of this proposal. One of the (very
> minor!) problems with lists in Haskell is that they can’t be
> documented with Haddock because they’re part of the syntax. For
> example, if you search Hoogle for `(:)` or `a -> [a] -> [a]` you
> won’t find the venerable list constructor. You will find `cons` from
> the `extra` package, which I think suggests that this proposal is a
> good idea.
>
> +1
>
> > On Sep 11, 2019, at 4:13 AM, Oliver Charles
> <ollie@ocharles.org.uk <mailto:ollie@ocharles.org.uk>> wrote:
> >
> > On Wed, Sep 11, 2019 at 7:36 AM Helmut Schmidt
> > <helmut.schmidt.4711@gmail.com
> <mailto:helmut.schmidt.4711@gmail.com>> wrote:
> >
> >> I can't be the only that wants this function, right?
> >
> > You're not the only one! I would also like this function. In fact,
> > only yesterday I found myself writing
> >
> > ( x : ) <$> recurse xs
> >
> > I would have preferred
> >
> > cons x <$> recurse xs
> >
> > +1 to adding cons :: x -> [x] -> [x] to Data.List.
> >
> > Ollie
> > _______________________________________________
> > Libraries mailing list
> > Libraries@haskell.org <mailto:Libraries@haskell.org>
> > http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries
>
>
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