Re: 答复: [Haskell-cafe] How to do this in FP way?

17 Jun 2008


      dons:
...
magicloud.magiclouds:
...
OK. Here it is.
I want to make a monitor tool for linux. It runs for a long time, and give
out a certain process's io stat per second. The way I get io stat is to read
from /proc/pid/io. But the data in this file is a total, I need to read it
first, then next second, read it again, and shows the difference, and go on.
So, what is your idea?
Easy,
import Control.Concurrent
    import Control.Monad
main = go 0
        where
            go st = forever $ do
                       n <- read `fmap` readFile "/proc/pid/io"
                       print (n - st) -- display difference
                       threadDelay (10^6)
Oops, not 'forever' :)

              go st = do
                    ...
                    go n

Re: 答复: [Haskell-cafe] How to do this in FP way?

Don Stewart