[Haskell-cafe] Re: Total Functional Programming in Haskell

[David Menendez]

On Wed, Oct 1, 2008 at 7:53 PM, wren ng thornton <wren at freegeek.org> wrote:
>
> [1] Just like existential types, you can put something in but you can never
> get it back out again. For inescapable monads like IO and ST, this is why
> they have the behavior of sucking your whole program into the existential
> black-hole.

That's true for IO, but the whole point of ST is that it *is*
escapable. What makes ST (and IO and STM) unusual is that it can't be
implemented in pure Haskell without special support from the run-time
system.
-- 
Dave Menendez <dave at zednenem.com>
<http://www.eyrie.org/~zednenem/>