Fri, 11 Jan 2002 22:56:24 +0000
> If I understand you correctly, you want global mutable variables, right?
> This is, I believe, only possible using IORef's and unsafePerformIO.
Kind of, I'm searching for the best approach to keep track of data in my
algorithms without constantly changing signatures.
State monad as defined in the paper I mentioned "monads for the working
haskell progarmmer" seemed the most elegant way. I saw ST in the Ghc and
thought it was supposed to do the same...
I never used mutable variables, but seems like it would prabably be the most
efficient way to do it, as for more elegant, I don't know... I'm thinking
about going for a simple State monad, no mutable variables... probably will
face some efficiency problems though...
> Something like this:
> | xRef :: IORef Int
> | xRef = unsafePerformIO $
> | newIORef 0
> | update_x :: IO ()
> | update_x = do
> | x <- readIORef xRef
> | writeIORef xRef (x+1)
> (Sorry for formatting, I'm using Outlook now :-)
> Of course this is not very functional, nice, safe or robust under compiler
> transformations (there probably should be a NOINLINE pragma there
And I was trying to get away from unsafePerformIO... :-)