Proposal [Trac #1212]: add IPv6 support to network library

[Bryan O'Sullivan]

Bryan O'Sullivan wrote:

> unpackBits :: Bits b => [(a, b)] -> b -> [a]
> 
> unpackBits mapping bits = foldl' unpack [] mapping
>     where unpack acc (k, v) | bits .&. v == 0 = acc
>                             | otherwise       = k:acc

Of course, this is stricter than it needs to be, and should use foldr 
instead of foldl'.  But I hope that the idea is useful nevertheless :-)

	<b