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

ajb at spamcop.net ajb at spamcop.net
Wed Jul 1 00:00:50 EDT 2009

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 <john at repetae.net>:

> 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 ||.

Andrew Bromage

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