Thanks all, I got it working finally. What did i learn ? a) I need to put a do after else for more than one instruction (?) b) All similar type of questions are to be redirected to haskell-beginner and haskell-cafe Points noted. Thank you once again, Abdullah Abdul Khadir On Wed, Nov 26, 2008 at 10:56 PM, wman <666wman@gmail.com> wrote:
if it should really read whole line, it must try to somehow chain the values into the string / list of chars (using (:) )
getMyLine :: IO [Char] getMyLine = do c <- getChar if (c == '\n') then return "" -- imho [] looks nicer ;-) else do rest <- getMyLine return $ c : rest
-- or
getMyLine :: IO [Char] getMyLine = do c <- getChar if (c == '\n') then return "" -- imho [] looks nicer ;-) else getMyLine >>= return . (c:)
-- or even shorter and still equivalent ;-)
getMyLine :: IO [Char] getMyLine = getChar >>= (\c -> if (c == '\n') then return [] else fmap (c:) getMyLine)
2008/11/26 abdullah abdul Khadir
Hi,
The function getMyLine written by me is intended for getting a complete string from the standard input.
import IO
getMyLine :: IO [Char] getMyLine = do c <- getChar if(c == '\n') then return "" else cs <- getMyLine return [c]
However I keep getting the following error:
io.hs:14:2: Parse error in pattern Failed, modules loaded: none.
I fail to understand what the error is. I tried out various things such as changing the alignment and so on to no avail. The following program, however, compiled successfully though it has the same structure as the previous program.
checkd :: IO Bool checkd = do c <- getChar if(c=='d') then return True else return False
Prelude> :load ./io.hs [1 of 1] Compiling Main ( io.hs, interpreted ) Ok, modules loaded: Main. *Main> checkd d True
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