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 <abdullah.ak2002@gmail.com>

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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