strict bits of datatypes
iavor.diatchki at gmail.com
Fri Mar 16 14:16:39 EDT 2007
I also think that the first version is the correct one (i.e., the
result is _|_).
On 3/16/07, Ross Paterson <ross at soi.city.ac.uk> wrote:
> On Fri, Mar 16, 2007 at 05:40:17PM +0100, apfelmus at quantentunnel.de wrote:
> > The translation
> > > q = FinCons 3 q
> > > === (by Haskell 98 report 4.2.1/Strictness Flags/Translation
> > > q = (FinCons $ 3) $! q
> > is rather subtle: the first FinCons is a strict constructor whereas the
> > second is "the real constructor". In other words, the translation loops
> > as we could (should?) apply
> > FinCons
> > => \x y -> FinCons x $! y
> > => \x y -> (\x' y' -> FinCons x' $! y') x $! y
> > => ...
> > ad infinitum.
> Yes, perhaps that ought to be fixed. But even so, this clearly implies that
> FinCons 3 _|_ = _|_
> and thus that q is _|_ and nhc98/yhc have a bug.
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