[Haskell-cafe] Alternative versus Monoid

Bas van Dijk v.dijk.bas at gmail.com
Fri Dec 16 14:56:29 CET 2011

On 16 December 2011 05:26, Brent Yorgey <byorgey at seas.upenn.edu> wrote:
> I, for one, would be
> quite in favor of changing the current Monoid (Maybe a) instance to
> correspond to the failure-and-prioritized-choice semantics

So lets do this. Some questions:

1) What about the First type? Do we {-# DEPRECATE #-} it?

2) What about the Last type? It could be deprecated in favor of Dual.

3) Do we need a new type (like the current Maybe) for lifting
semigroups into a Monoid? IMHO we don't since the semigroup package
does a better job with the Option type (like Brent mentioned).

4) How much code will break from this change?

5) Anyone up for proposing this to libraries at haskell.org?



More information about the Libraries mailing list