[Haskell-beginners] redirect stdout to /dev/null

On UNIX, we can easily redirect stdout to /dev/null in a Shell. How is this realized in Haskell on both UNIX and Windows? I used a library which gave me unwanted stdout display. I tried to find any function to hide the stdout output, but could not. Can someone help me out? Otherwise I have to modify the code in the library to comment out some print commands. Thanks, Hong