Re: [Haskell-beginners] Given a list of lists, how to drop the last item in each (sub)list.

I like that :) On 2 January 2014 15:31, wrote:

Hi Angus! Take a look at the following function:

discardParityByte :: [[Integer]] -> [[Integer]] discardParityByte = map init

It returns a list constructed by applying "init" to all items in the list you pass in. "init" accepts a list and returns the list without its last item.

Stavros Mekesis.

Quoting Angus Comber :

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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