Primary idea was to keep error messages. OK, I done it with `State` monad :) Thank you!

Hi,

1. I think your data type is isomorphic to

data Allpass w m a = Pass Bool (m a) w

2. Maybe first try to write a Functor instance? Then you can find out what constraints are necessary for 'w' and 'm' to write it.

3. What does this data type intend to represent?

Best,

toz

On Wed, Oct 25, 2017 at 5:32 AM wrote:

...

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Today's Topics:

1. Is it possible such Monad? (Baa)

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Message: 1 Date: Wed, 25 Oct 2017 13:56:31 +0300 From: Baa To: The Haskell-Beginners Mailing List - Discussion of primarily beginner-level topics related to Haskell Subject: [Haskell-beginners] Is it possible such Monad? Message-ID: <20171025135631.1f9913d2@Pavel> Content-Type: text/plain; charset=US-ASCII

Hello All!

Is it possible to write Monad for such type:

data Allpass w m a = Nopass (m a) w | Allpass (m a) w

I can write (>>=), IMHO such type can not be Monad due to `w` is not under `m` monad, right?

=== Best regards, Paul

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