[Haskell-cafe] Is it acceptable if Applicative behave not like a Monad

[Omari Norman]

On Thu, Apr 30, 2015 at 1:32 PM, Nikita Volkov <nikita.y.volkov at mail.ru>
wrote:

> I'm afraid I have to disagree with Adam as well. Recently I've triggered a
> prolonged discussion on exactly the subject (
> https://github.com/ekmett/either/pull/38). Being originally convinced
> that the instances can behave however it fits, I think I've been
> over-persuaded in the end.
>
> Shortly speaking, while I can't say I like it, the rule seems to be that
> `<*>` should produce the same side effects as Monad's `ap`.
>
>
One example of a library where the Applicative and Monad instances mismatch
is uu-parsinglib.

http://stackoverflow.com/questions/18275123/cannot-compute-minimal-length-of-a-parser-uu-parsinglib-in-haskell/18292328#18292328

There's a good reason the library is this way but the behavior can be
rather startling.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/haskell-cafe/attachments/20150430/de33345c/attachment.html>