[Haskell-cafe] Type system madness

Lennart Augustsson lennart at augustsson.net
Wed Jul 11 16:13:56 EDT 2007


Well, Haskell defines the IO type to be abstract, so if IO and ST happen to
be the same it's implementation dependent.

  -- Lennart

On 7/11/07, Bulat Ziganshin <bulat.ziganshin at gmail.com> wrote:
>
> Hello Andrew,
>
> Tuesday, July 10, 2007, 11:49:37 PM, you wrote:
>
> >>> ...so the 's' doesn't really "exist", it's just random hackery of the
> >>> type system to implement uniqueness?
> >>>
> >>
> >> Exactly.
> >>
>
> > Hmm. Like the IO monad's RealWorld object, which isn't really there?
>
> ST and IO monads are the same beast. in ST, s is free to allow to
> create endless amount of independent threads while in IO it fixed to
> one type and describes evolution of one thread, synchronized with real
> world. look at http://haskell.org/haskellwiki/IO_inside for info about
> IO monad trickery
>
>
> --
> Best regards,
> Bulat                            mailto:Bulat.Ziganshin at gmail.com
>
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