a readFile problem

Hallo, I have the following problem: my program asks the user for a command, when the command is executed a new command is asked (this is no problem ; an example is in the HUgs distribution namely Main.hs in the Prolog example. However one of the commands is: read filename i.e. read a file and display it. I do not succeed in implementing this. Could anyone give an example of: reading commands in a loop where one of the commands is the read command mentionned above. Or is it not possible in Haskell? I have already wated a lot of time on this, so if anyone gives me an answer I will be very gratefull. Greetings,