Thanks both for the the explanation and the link. The wikibook is really
growing fast!
Abhay
On Wed, May 7, 2008 at 5:05 PM, apfelmus <[EMAIL PROTECTED]> wrote:
> Abhay Parvate wrote:
>
> > Just for curiocity, is there a practically useful computation that uses
> > 'seq' in an essential manner, i.e. apart from the efficiency reasons?
> >
>
> I don't think so because you can always replace seq with const id .
> In fact, doing so will get you "more" results, i.e. a computation that
> did not terminate may do so now.
>
> In other words, we have
>
> seq _|_ = _|_
> seq x = id for x > _|_
>
> but
>
> (const id) _|_ = id
> (const id) x = id for x > _|_
>
> So, (const id) is always more defined (">") than seq .
>
>
> For more about _|_ and the semantic approximation order, see
>
> http://en.wikibooks.org/wiki/Haskell/Denotational_semantics
>
>
>
> Regards,
> apfelmus
>
>
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