[Haskell-cafe] instance Alternative (Either [a])

Kim-Ee Yeoh ky3 at atamo.com
Thu May 22 10:33:29 UTC 2014


On Thu, May 22, 2014 at 2:10 PM, Tony Morris <tmorris at tmorris.net> wrote:

> AccValidation has an Applicative instance that accumulates on "Left"
> (Failure) as per the previous email. Therefore, it has no Monad.
>
> Validation has a Monad and Applicative the same as Either.


Thanks for clarifying. So my takeaway is that

1) Validation instead of Either is not so much bikeshedding on the name as
aligning with the use-case of AccValidation, and

2) AccValidation vs Either is like the ZippyList applicative vs List monad
conflation.

-- Kim-Ee
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