Hi folks, I'm finishing up my Haskell interface to WordNet (http://www.cogsci.princeton.edu/~wn/) and have a standard unsafePerformIO question :). Basically, the interface functions by first calling an initialization function, 'initializeWordNet :: IO WordNetEnv'. WordNetEnv is essentially just a record of a lot of Handles which we will be reading from and doing binary search in. All the functions which use the WordNetEnv (i.e., every other function in the interface) basically do the following: - take one handle from the WordNetEnv and do binary search in it, read a line. - use that line to read another line from another of the handles - parse that last one of course, therefore, all of these functions have type '... -> IO something'. However, one of the "rules of thumb" for using unsafePerformIO is when you can imagine a functional interface doing the same thing. I can: simply read in all the databases in initializeWordNet and then do Data.List.lookup on the results. Does this mean it's safe to wrap all these functions in unsafePerformIO? If not, I'll probably just create a WordNet Reader monad and wrap things up like that -- if you have to be in a monad anyway, there's no reason to pass the WordNetEnv around everywhere. But still, if possible, it would be nice for these to be pure. - Hal -- Hal Daume III | hdaume@isi.edu "Arrest this man, he talks in maths." | www.isi.edu/~hdaume