A while ago Alastair pointed me towards a patch that fixed this
bug. I patched our UNIX version of hugs1.4 and now it works great
does anyone have a windows95 executable of hugs1.4 that has been
compiled with this patch? I dont have a windows95 C compiler.
thanks.
byron
On Mon, 7 Jul 1997, Mark P Jones wrote:
> | Hugs 1.4 doesn't like the demos/ldfs.hs: it says there's a type error in
> | the runST application. (Try `hugs ldfs'...) It that a bug?
>
> Yes, there is a bug in the way that the runST construct is handled in the
> current betas of Hugs 1.4. We hope to have this ironed out real soon now.
>
> | (By the way, what's the type of runST?)
>
> Like "if" or "where", "runST" is a keyword in a language construct, and
> not a value that would have a type. There is, however, a typing rule for
> the runST contruct, roughly something like:
>
> A |- E : forall s . ST s a
> ----------------------------
> A |- runST E : a
>
> Unfortunately, the original Launchbury/Peyton Jones rules for typing runST
> did not specify how class constraints/predicates in languages like Haskell
> should be dealt with in typing runST. There are several different choices,
> and the error you've seen is probably just an indication that we didn't
> pick the most flexible option.
>
> All the best,
> Mark
>
