Re: [Haskell-cafe] Monoid wants a (++) equivalent

On Wed, Jul 01, 2009 at 12:00:50AM -0400, ajb@spamcop.net wrote:

G'day all.

On Tue, Jun 30, 2009 at 08:02:48PM -0400, Daniel Peebles wrote:

...

But we don't want to imply it's commutative either. Having something "bidirectional" like <> or <+> feels more commutative than associative to me.

Quoting John Meacham :

...

Not really, think of '++', which doesn't commute but is visually symmetric, or Data.Sequence.<>, or the common use of <> to mean concatination in pretty printers.

Other good examples are && and ||.

..wha? But those ARE commutative. Unless you mean with respect to strictness? -Brent