[Haskell-beginners] How to get each list in a list of lists for filter

[Angus Comber]

I am getting a list of lists from chop9.  I want to somehow filter each
element in the list.  How do I do that.

I have encoded binary data eg [1,1,0,0,1,0] etc

Each 9th bit is a parity bit which is checked using this function:

type Bit = Int

paritychecker :: [Bit] -> Bool
paritychecker xs | length xs == 9 && ((sum (init xs)) `mod` 2) == (last xs)
= True
                 | otherwise = False


In the stream (the list) I use chop to retrieve each block of 9 bits as in:

chop9 :: [Bit] -> [[Bit]]
chop9 [] = []
chop9 bits = take 8 bits : chop9 (drop 8 bits)

I have been playing with this sort of thing:
filter paritychecker ??? chop9 [1,0,0,0,1,1,1,0,0,...]

But doesn't work.

I want to end up with all the 9 bit chunks which pass the filter.  So my
end type should be [[Bit]]

paritychecker requires a list - eg [Bit] . So I want to run paritychecker
on each element returned from chop9.  How do I do that?

Example encoded data stream:
[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]

Angus
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