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

Tony Morris tmorris at tmorris.net
Thu May 22 07:10:24 UTC 2014

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.

On Thu, May 22, 2014 at 2:18 PM, Kim-Ee Yeoh <ky3 at atamo.com> wrote:

> On Thu, May 22, 2014 at 6:58 AM, Tony Morris <tmorris at tmorris.net> wrote:
>> http://hackage.haskell.org/package/validation-0.3.4/docs/Data-Validation.html
> I don't understand how to use this package.
> Is it because Either is an ugly name for the data type and Validation is
> preferable?
> And AccValidation is to be used over Validation, like in Hungarian
> notation, to indicate (the possibility of?) a Semigroup instance on Left /
> Failure?
> -- Kim-Ee
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