Hi, I am newbie, reading the Gentle Introduction. Chapter 7 (Input/Output) says Pragmatically, it may seem that getContents must immediately read an entire file or channel, resulting in poor space and time performance under certain conditions. However, this is not the case. The key point is that getContents returns a "lazy" (i.e. non-strict) list of characters (recall that strings are just lists of characters in Haskell), whose elements are read "by demand" just like any other list. An implementation can be expected to implement this demand-driven behavior by reading one character at a time from the file as they are required by the computation. So what happens if I do contents <- getContents handle putStr (take 5 contents) -- assume that the implementation -- only reads a few chars -- delete the file in some way putStr (take 500 contents) -- but the file is not there now If an IO function is lazy, doesn't that break sequentiality? Sorry if the question is stupid. Thanks, Tamas