[Haskell-cafe] AMP - how do you motivate this in teaching?

Erik Hesselink hesselink at gmail.com
Fri Nov 20 09:31:48 UTC 2015

On 20 November 2015 at 02:30, Manuel Gómez <targen at gmail.com> wrote:
> I haven’t found a helpful example of an Applicative that is not a Monad
> that is practical for a lesson.

There's ZipList [0], which depending on the type of audience might be
doable. There's also Const [1], but that needs a Monoid constraint,
and since you said you considered ((,) e) as not having an
Applicative, which it does have with a Monoid constraint, perhaps
Const isn't suitable to you for that reason. There are more
interesting examples here [2].


[0] https://hackage.haskell.org/package/base-
[1] http://hackage.haskell.org/package/base-
[2] http://stackoverflow.com/questions/7220436/good-examples-of-not-a-functor-functor-applicative-monad

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