Using existential types

[Tomasz Zielonka]

On Fri, Oct 03, 2003 at 09:42:48AM +0200, Tomasz Zielonka wrote:
> However this approach has caveats. For example you can't store the state
> of Stat and restart it later. All steps are done within one call to
> runStat.

I was wrong. I can write:

updateStat :: Stat i o -> i -> Stat i o
updateStat (Stat init update result) i = (Stat (update init i) update result)

Best regards,
Tom