I don't think anyone has claimed that any interface can be implemented without globals. Of course some can't (just pick an interface that is the specification of a global variable).
What I (and others) claims is that such interfaces are bad. Using a global variable makes an assumption that there's only ever going to be one of something, and that's just an inflexible assumption to make. You think global variables are essential, I think they are a sign of bad design. So we have different opinions and neither one of us is going to convince the other. I think a lot of things related to the IO monad in Haskell is bad design; influenced by imperative thinking. For instance, I think the main function should have a type like main :: (IOMonad io) => io a where IOMonad contains some basic functionality like calling C. Then you could do things like implement runInsandboxIO which traces all C calls. -- Lennart On Thu, Aug 28, 2008 at 5:26 PM, Adrian Hey <[EMAIL PROTECTED]> wrote: > Jonathan Cast wrote: >> >> On Thu, 2008-08-28 at 10:00 +0100, Adrian Hey wrote: >>> >>> Lennart Augustsson wrote: >>> > I don't don't think global variables should be banned, I just think >>> > they should be severly discouraged. >>> >>> If you're saying a language should not provide a sound way to do >>> this (as I believe you are), then AFAICT for all practical purposes >>> you *are* saying you think global variables should be banned. >>> >>> Where are we going to be if the unsafePerformIO hack ever becomes >>> *really* unsafe? >>> >>> and.. >>> >>>> I'm certain you can write a kernel in Haskell where the only use of >>>> global variables is those that hardware interfacing forces you to use. >>> >>> But what you haven't explained is why this is even desirable? I don't >>> doubt it's true in an academic sense if you don't mind sacrificing >>> safety >> >> What `safety' is being sacrificed? >> >>> and modularity. >> >> What modularity? > > As I've pointed out several times already you can find simple examples > in the standard haskell libs. So far nobody has accepted my challenge to > re-implement any of these "competantly" (I.E. avoiding the use of global > variables). > > Why don't you try it with Data.Unique and find out :-) > > Regards > -- > Adrian Hey > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
