On 19 December 2010 21:27, ender <crazyen...@gmail.com> wrote: > Hi all: > I'v been learning haskell for several months, and now I'm trying > to write some "real word" program in haskell, like finding files under > one directory or something > My problem is that, I dont know the way of writing a loop in > haskell. I searched google and found some code that translate c loop > into haskell like this one: > >> > > I am new to haskell and would look to write a function equivalent >> > > to the following loop in C >> > > >> > > int value = 500000; >> > > int part_stack[4]; >> > > int *part_ptr = part_stack; >> > > for (; value; value /= 10000) >> > > *part_ptr++ = value % 10000; >> > >> > part_stack :: [Int] >> > part_stack = [0,50] >> > >> > Note that I've performed a memoization optimization--this >> > makes the code both smaller, faster and easier to read! :P >> >> Ignore David, he's pulling your leg. Here's the proper translation: >> >> do >> alloca $ \value -> do >> poke value (500000::Int) >> allocaArray 4 $ \part_stack -> do >> alloca $ \part_ptr -> do >> poke part_ptr part_stack >> let loop = do >> val <- peek value >> if val == 0 then return () else do >> p <- peek part_ptr >> poke p (val `rem` 10000) >> poke part_ptr (p `plusPtr` 1) >> poke value (val `quot` 10000) >> loop >> loop > > and I really think that's not a "haskell way", it's just translate c > code into haskell code byte by byte > My question is: how to translate above c code into haskell in "haskell way"
Short answer: you don't. Longer answer: have a read through http://book.realworldhaskell.org/read/io-case-study-a-library-for-searching-the-filesystem.html -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
