Proposal: Add First and Last wrappers around Maybe to Data.Monoid

Spencer Janssen sjanssen at
Mon Mar 12 15:41:43 EDT 2007

I'd like to note that the behavior for this Maybe instance is quite
different from what you get with MonadPlus.  This seems inconsistent
with respect to the instances of MonadPlus and Monoid for lists.

I realize I'm objecting in the 11th hour, but I think this requires
some consideration.

Spencer Janssen

On Mon, 12 Mar 2007 08:10:24 -0800
"Jeffrey Yasskin" <jyasskin at> wrote:

> Today is the scheduled end for discussion on this proposal. Are there
> any final objections, suggestions, or comments before I update the
> ticket and ask someone to commit it?
> On 3/8/07, Jeffrey Yasskin <jyasskin at> wrote:
> > I've attached a second version of the patch to the ticket
> > ( along with the
> > HTML Haddock generates from it. I added the two examples and the
> > "imposed identity" instance directly on Maybe. Would one of its
> > fans like to provide an example of using the Maybe monoid?
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