[Haskell-cafe] Monad explanation

Miguel Mitrofanov miguelimo38 at yandex.ru
Thu Feb 5 14:41:10 EST 2009


Ahem... WHAT??? IO monad is impure??? What do you mean?

On 5 Feb 2009, at 22:25, Andrew Wagner wrote:

> I think the point of the Monad is that it works as a container of  
> stuff, that still allows mathematically pure things to happen, while  
> possibly having some opaque "other stuff" going on.
>
>  This at least sounds, very wrong, even if it's not. Monads are not  
> impure. IO is, but it's only _one_ instance of Monad. All others, as  
> far as I know, are pure. It's just that the bind operation allows  
> you to hide the stuff you don't want to have to worry about, that  
> should happen every time you compose two monadic actions.
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