On 8 Nov 2004, at 12:23, Lennart Augustsson wrote:
Adrian Hey wrote:
4- They already exist (stdin,stout,stderr) and I don't recall anybody ever complaining about this.
stdin, stdout, and stderr are not global variables. They are just handles. One possible implementation of handles is as an Int. So stdin is no more a global variable than 0. Of course you need some state associated with the handle, but that state does not have to be a unique global things. You are passing that state around via the IO monad, and there could be multiple versions of it. GHC chooses to implement it differently, but that's a choice.
Yes... a lot of the example we have seen here are 'just' handles. newIORef creates handles. Something many programmers would like is the ability to create fresh handles at the toplevel... Jules