David Sabel
Tue, 17 Sep 2002 15:58:03 +0200

> I think the query
> originally
> assumed a sequencing ambiguity in the IO monad... but in my experiance
> (all be it  limited) the IO monad is there to ensure strict sequencing.

You're right, this was my main question. I read the paper "Tackling the
Awkwar Squad: monadic input / output, concurrency, exceptions, and
foreign-language calls in Haskell", Simon Peyton Jones, available at

There is an operational semantic given for the IO system,
and  I think this semantic ensures strict sequencing of IO actions.

In this paper the echoTwice-example is given, and I was a little bit
confused about the abnormal behavior of the program when I executed it.
I didn't think at the buffering, but now it seem to be clear...

Thanks for your comments

David Sabel
JWGU Frankfurt