[Haskell-cafe] Monad explanation

[Lennart Augustsson]

Not it doesn't.  getChar has the type signature IO Char.
The IO type is abstract.  GHC happens to implement it by a state monad.
But in, e.g., hbc it is implemented in a totally different way,
more like a continuation monad.

Peeking inside an implementation of IO can be illuminating,
but one must remember that IO is abstract.

  -- Lennart

On Mon, Feb 9, 2009 at 10:26 AM, Tony Morris <tmorris at tmorris.net> wrote:
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> Gregg Reynolds wrote:
>> The point being that the metalanguage commonly used to describe IO
>> in Haskell contains a logical contradiction.  A thing cannot be both
>> a value and a function, but e,g, getChar behaves like a function and
>> has the type signature of a value.
> getChar has the signature RealWorld -> (RealWorld, Char)
>
> - --
> Tony Morris
> http://tmorris.net/
>
> *********************************************************
> * Anteromedial Heterotopic Osseous Impingement Syndrome *
> *********************************************************
>
> http://www.ajronline.org/cgi/content/full/178/3/601
> "can result in chronic ankle pain, especially in athletes and the
> younger population (15-40 years old)"
>
> http://radiographics.rsnajnls.org/cgi/content/figsonly/22/6/1457
> "Soft-tissue and osseous impingement syndromes of the ankle can be an
> important cause of chronic pain, particularly in the professional
> athlete."
>
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