Hello, Thanks for the tip. Im stuck now. I have this : halve (xs) | length xs'mod'2 == 0 = (take n xs drop n xs) | otherwise = (take n+1 xs drop n+1 xs where n= lenght xs'div'2 main = do putStrLn $ show $ halve [1,2,3,4] putStrLn $ show $ halve [1,2,3] But now I get this message : ERROR line 3 - Syntax error in expression (unexpected keyword "where") Appearently I can't use where here. How can I solve this ? Roelof

Date: Mon, 11 Jul 2011 11:44:28 -0400 Subject: Re: [Haskell-beginners] function defenition. Do I understand it right? From: dmcbride@neondsl.com To: rwobben@hotmail.com CC: beginners@haskell.org

For simple snippets like this, you can go to http://codepad.org/ddySVOPr and run your code to see if it works.

And your first version (once corrected for syntax) works on any list length except for empty lists.

On Mon, Jul 11, 2011 at 10:48 AM, Roelof Wobben wrote:

...

Hello,

I have made a exercise where I must split a even list. The answer is :

halve xs = (take n xs drop n xs) where n = length xs 'div' 2

Now I want to change it so i can split even and not even list,. I thought this can be the answer

halve xs = lenght xs 'mod' 2 = 0 : (take n xs drop n xs) otherwise : (take n+1 xs drop n+1 xs) where n = length xs 'div' 2

Can this be working ? I did not check this on GCHI because Im re - installing my OS.

Regards.

Roelof

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Because I tried it and it didn't work. But it turns out it does work and it was just an ambiguous variable error from using empty list. Codepad had a weird error, they must be using an old version of ghc or something. On Mon, Jul 11, 2011 at 6:17 PM, Ozgur Akgun wrote:

Hi.

On 11 July 2011 18:44, David McBride wrote:

...

And your first version (once corrected for syntax) works on any list length except for empty lists.

Why wouldn't it work for empty lists? For example with the following definition: halve xs = let n = length xs `div` 2 in (take n xs, drop n xs)

Best, Ozgur