The definition of getLine given in 8.3: getLine :: IO String getLine = do c <- getChar if c == '\n' then return "" else do s <- getLine return (c:s) is incorrect in view of 7.1: The getLine operation raises an exception under the same circumstances as hGetLine, defined [in] the IO library. ("in" is missing from the published Report.) 21.9.2: The hGetLine computation fails with isEOFError if the end of file is encountered when reading the first character of the line. If hGetLine encounters end-of-file at any other point while reading in a line, it is treated as a line terminator and the (partial) line is returned.