[Haskell-beginners] Trying to find an alternative StateMonad

[Patrick LeBoutillier]

Hi,

Sorry I can't be of much help here, but I have a question though:

>
> data StateCmd a where
>        Put :: a -> StateCmd a
>        Undo :: StateCmd a
>        Redo :: StateCmd a
>                deriving (Show, Functor)

I'm not familiar with the above syntax (data ... where). What does it
do exactly?

Patrick



-- 
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Patrick LeBoutillier
Rosemère, Québec, Canada