2014 Applicative => Monad proposal

David Luposchainsky dluposchainsky at googlemail.com
Wed Jun 5 20:54:01 CEST 2013

On 2013-06-05 20:08, Daniel Díaz Casanueva wrote:
> I am excited about this proposal, and I really hopes it will be 
> performed. I have been following the discussion for a long time,
> always perceiving that Applicative as a superclass of Monad is the
> right thing to do. As a consequence, Functor will also be a
> superclass of Monad. This changes may affect my code, but I will be
> glad to make any changes.

If your code ...
- does not use the names join, <*> or pure outside of their
  Applicative/Monad context
- includes Applicative instances for all Monads
... there is nothing to change. Boring, I know.

> Also, I am wondering if our agreement to implement this proposal
> would imply an Applicative class being included in a future Haskell
> Report.

The libraries mailing list does not decide changes to the Report. That
said, the long term plan is changing the Report, preferrably in the next
iteration, and getting GHC and Hackage ready for it is the most
important step towards it. Although when these changes are made I see no
reason not to make the AMP official, it remains speculation at this point.


More information about the Libraries mailing list