The Revenge of Finalizers

Ross Paterson ross at
Thu Oct 17 13:10:18 EDT 2002

On Thu, Oct 17, 2002 at 10:09:06AM +0100, Simon Marlow wrote:
> > There's another problem with Simon's patch I haven't been able to pin
> > down: if you run the example, interrupt it at the right point and type
> > another expression, the finalizers run, but the expression is lost.
> I can get it to fail another way too:
>   main = do
>     p <- mallocBytes 64
>     newForeignPtr p (print x)
>     print x
>    where
>     x = sum [1..10000]
> Can't believe I didn't realise this kind of thing might be a problem
> before... guess I was too fixated on the other issues.  Anyway, it
> really needs someone who is familiar with the Hugs backend to comment on
> whether either of these problems are fixable or not.

I can fix mine, though not yours: it's necessary to wrap runFinalizers()
in push(n) ... drop(), so the garbage collector will see n.

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