Thanks all,<br> I got it working finally. What did i learn ?<br>a) I need to put a do after else for more than one instruction (?)<br>b) All similar type of questions are to be redirected to haskell-beginner and haskell-cafe<br>
<br>Points noted. <br>Thank you once again,<br>Abdullah Abdul Khadir<br><br><br><br><div class="gmail_quote">On Wed, Nov 26, 2008 at 10:56 PM, wman <span dir="ltr"><<a href="mailto:666wman@gmail.com">666wman@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">if it should really read whole line, it must try to somehow chain the values into the string / list of chars (using (:) )<div class="Ih2E3d">
<br><br>getMyLine :: IO [Char]<br>
getMyLine = do<br>
c <- getChar<br>
if (c == '\n')<br></div>
then return "" -- imho [] looks nicer ;-)<br>
else do<br> rest <- getMyLine<br> return $ c : rest<br>
<br>-- or<div class="Ih2E3d"><br><br>getMyLine :: IO [Char]<br>getMyLine = do<br> c <- getChar<br> if (c == '\n')<br></div> then return "" -- imho [] looks nicer ;-)<br> else getMyLine >>= return . (c:)<br>
<br>
-- or even shorter and still equivalent ;-)<br><br>getMyLine :: IO [Char]<br>getMyLine = getChar >>= (\c -> if (c == '\n') then return [] else fmap (c:) getMyLine)<br><br><br><br><div class="gmail_quote">
2008/11/26 abdullah abdul Khadir <span dir="ltr"><<a href="mailto:abdullah.ak2002@gmail.com" target="_blank">abdullah.ak2002@gmail.com</a>></span><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div><div></div><div class="Wj3C7c">
Hi,<br><br> The function getMyLine written by me is intended for getting a complete string from the standard input. <br><br>import IO <br><div><div></div><div><br>getMyLine :: IO [Char]<br>
getMyLine = do<br>
c <- getChar<br>
if(c == '\n')<br>
then return ""<br>
else cs <- getMyLine<br>
return [c]<br>
<br></div></div>However I keep getting the following error:<br><br>io.hs:14:2: Parse error in pattern<br>Failed, modules loaded: none.<br><br> 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. <br>
<br>checkd :: IO Bool<br>
checkd = do<br>
c <- getChar<br>
if(c=='d')<br>
then return True<br>
else return False<br>
<br>
Prelude> :load ./io.hs<br>[1 of 1] Compiling Main ( io.hs, interpreted )<br>Ok, modules loaded: Main.<br>*Main> checkd<br>d<br>True<br><br>
<br></div></div><div class="Ih2E3d">_______________________________________________<br>
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<br></div></blockquote></div><br>
</blockquote></div><br>