[Haskell-cafe] Proposal #3339: Add (+>) as a synonym for mappend

Edward Kmett ekmett at gmail.com
Sun Aug 14 22:31:01 CEST 2011

I originally didn't have the package exporting those things.

I would be amenable to standardization without them, but I use them in about
20 packages that are built on top of semigroups, and naturals and non-empty
lists come up when talking about semigroups a lot.

Rather than having them live way up in extension land with the rest of my
algebra libraries i moved them down to where they could do some good and
admit some optimizations.

On Sun, Aug 14, 2011 at 2:21 PM, Chris Smith <cdsmith at gmail.com> wrote:

> On Sun, 2011-08-14 at 21:05 +0300, Yitzchak Gale wrote:
> > Brandon Allbery wrote:
> > > Anything useful has to be modified to depend on SemiGroup as well to
> get
> > > mconcat or its replacement; that's why you jumped the proposal to begin
> > > with....
> >
> > Not at all. Types with Monoid instances need an additional
> > instance, a Semgroup instance
> That does require depending on semigroups though, and I think that's
> what Brandon was saying.
> Of course, the obvious solution to this would be to promote semigroups,
> e.g., by adding it to the Haskell Platform or including it in base...
> but the current semigroups package is a bit heavyweight for that; it
> exports four new modules for what is really a very simple concept!
> --
> Chris Smith
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