8 Nov
2004
8 Nov
'04
7:14 a.m.
Adrian Hey wrote:
Why are top level IORefs any worse than other IORefs (for example)?
Because global variables are just BAD. They have been considered bad a long time, it's not a Haskell thing. If you really grok the functional way of doing things there should be *very*, *very* few times you need a global variable. I incredibly suspicious about code that "needs" it. Having a global variable almost always you have a single copy of some data structure; there is no way to create two of them. I claim that the right way is to have a handle to your "object" and pass that around. (But I can also be persuaded that there might be exceptions. (I've written a few lines of Haskell and I have used a global variable once, I think.)) -- Lennart