It's usually much simpler and better design to think about the simple case first and then piece things together. So start with just modifying one inner list:

discardparitybyte :: [Bit] -> [Bit]

discardparitybyte xs = take 9 xs

When you're happy that this works, you can apply it to all the elements of your data list:

discardallparitybytes :: [[Bit]] -> [[Bit]]

discardallparitybytes xs = map discardparitybye xs

And, if you want to, you can make it shorted by making the functions point-free:

discardparitybyte = take 9

discardallparitybytes = map discardparitybye

Peter

On 2 January 2014 11:38, Angus Comber <anguscomber@gmail.com> wrote:

I have a list like this:

[[1,0,0,0,1,1,1,0,0],[1,1,1,0,1,1,1,0,0],[1,0,1,0,0,1,1,0,0],[0,1,0,0,1,1,1,0,0],[0,0,1,0,1,1,1,0,0],[1,0,0,1,1,1,1,0,1]]

The 'inner' list is a list of 9 items. I want to process the list so that a list of lists is returned but the 9th element in each inner list is dropped.

So the function type would be [[a]] -> [[a]]

So to get started I wrote a function like this:

discardparitybyte :: [[Bit]] -> [[Bit]]

But then not sure how to transform the inner list.

I know I can access the first inner element using take 1 list. But how do I then access/manipulate this inner list?

discardparitybyte (x:xs) = take 9 ??? (take 1 xs) : discardparitybyte ???

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