[Haskell-cafe] Monoid wants a (++) equivalent
pumpkingod at gmail.com
Tue Jun 30 20:02:48 EDT 2009
But we don't want to imply it's commutative either. Having something
"bidirectional" like <> or <+> feels more commutative than associative
On Tue, Jun 30, 2009 at 6:39 PM, John Meacham<john at repetae.net> wrote:
> On Tue, Jun 30, 2009 at 02:54:38PM -0400, Brent Yorgey wrote:
>> On Tue, Jun 30, 2009 at 09:45:45AM -0700, Bryan O'Sullivan wrote:
>> > I've thought for a while that it would be very nice indeed if the Monoid
>> > class had a more concise operator for infix appending than "a `mappend` b".
>> > I wonder if other people are of a similar opinion, and if so, whether this
>> > is worth submitting a libraries@ proposal over.
>> IIRC Jules Bean has proposed using (+>) for this purpose, which I
>> like. It has the advantages of (a) not clashing with any other
>> (common) operators, (b) making more obvious the fact that mappend is
>> not necessarily commutative, and (c) providing the obvious (<+) for
>> 'flip mappend' which is sometimes useful.
> (+>) seems to imply to me that the operator is non-associative. Something
> like (<>) or (<+>) would be better.
> John Meacham - ⑆repetae.net⑆john⑈ - http://notanumber.net/
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