[Haskell-cafe] Why no IO transformer monad?

[Philippa Cowderoy]

On Sat, 18 Dec 2004, Henning Sato von Rosen wrote:

> But, I am working on understanding IO magic, on a much more concrete
> level, so I am am looking for a really good explanation of the above.
> (And the IO monad in general.)
>

One way of looking at it is that a monad is an interpreter that has access 
to a haskell interpreter (typically called by return). You can't write an 
IO interpreter in terms of anything else, so you can't layer it on top of 
something - it's got to be on the bottom of the stack.

-- 
flippa at flippac.org

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