FW: RE [Haskell-cafe] Monad Description For Imperative Programmer

[Jeff Polakow]

Hello,

> 'Monad' is a type class.
> 
> So what's 'IO'? Is the correct terminology 'instance' as in 'IO is an
> instance of Monad'. I consider 'IO' to be 'a monad' as that fits with
> mathematical terminology. 
>
I agree with this.

>But what about an actual object of type 'IO
> Int', say? 
>
I usually describe the type resulting from applying a monad a computation. 
Then 'IO Int' would be something like an IO computation of an Int. This 
terminology also jibes well with, or rather comes from, Moggi's 
computational lambda calculus (one of the early papers showing uses of 
Monads to computer science).

-Jeff


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