deeqSeq proposal

[Spencer Janssen]

How about an implementation that sets the deepSeq'd bit *after* each
field has been successfully deepSeq'd?  deepSeq'ing a cyclic structure
would behave just like an infinite structure.


Spencer Janssen

On 4/4/06, Simon Marlow <simonmar at microsoft.com> wrote:
> On 30 March 2006 23:12, Andy Gill wrote:
>
> > Implementation:
> >
> > deepSeq (RAW_CONS <is_deep_seq'd_bit> ... fields ) =
> >      if <is_deep_seq'd_bit> == True
> >          then return  /* hey, we've already deepSeq'd this */
> >          else set <is_deep_seq'd_bit> to True.
> >                   deepSeq (field_1)
> >                   ...
> >                   deepSeq (field_n)
> > deepSEQ (REF/MVAR...) = return
>
> So deepSeq doesn't return _|_ when passed a cyclic structure?  This is a
> bad idea, because it lets you distinguish cyclic structures from
> infinite ones.  deepSeq has to behave like a function, regardless of its
> implementation.
>
> Cheers,
>         Simon
> _______________________________________________
> Haskell-prime mailing list
> Haskell-prime at haskell.org
> http://haskell.org/mailman/listinfo/haskell-prime
>