"Glynn Clements" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] > > Srinivas Nedunuri wrote: > > > Hello, I have some code that manipulates STRefs within the ST monad. All > > good and fine, until I come across some computation that uses lets say > > IO and everything skids to a halt. At this point I have 3 choices: > > > > 1. Define a ST State Transformer monad and do all my previous ST > > computations in that > > 2. convert all subsequent ST computations into IO computations using > > stToIO > > 3. stop using the ST monad and do everything in the IO monad > > > > I was wondering what advice folks had. In particular, what are the > > disadvantages to doing everything in the IO monad - ie why even bother > > with the ST monad? > > The most obvious disadvantage is that the IO monad has no equivalent > of runST. OK, I'm missing something here. What is the big deal about runST? Can I not get the IO equivalent by simply running the program at the top level (assuming I don't have multiple threads going). Do you have a practical example of needing runST in several places in your program?
> Also, there is no ioToST (only unsafeIOToST), so if you use > the IO monad, the code can only be used within the IO monad. The IO > monad is like a "trap"; once your inside, you can't get out. True but I'm effectively trappend now anyway. I have a bunch of ST code, and then somewhere in there I had the misfortune of needing to insert a file copy and bam I'm now stuck with the dang IO monad which goes and "infects" the entire program. > > -- > Glynn Clements <[EMAIL PROTECTED]> _______________________________________________ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
