On Sat, 2011-01-01 at 19:27 +1100, Jesse Schalken wrote: > > On Sat, Jan 1, 2011 at 8:54 AM, Felipe Almeida Lessa > <felipe.le...@gmail.com> wrote: > On Fri, Dec 31, 2010 at 6:43 PM, aditya siram > <aditya.si...@gmail.com> wrote: > > -- untested and won't work on an infinite list > > last :: [a] -> a > > last = head . reverse > > > No definition for last works with infinite lists =). > > > Unless you make the result nullable, of course. > > > maybeLast :: [a] -> Maybe a > > maybeLast [] = Nothing > maybeLast [x] = Just x > maybeLast (_:xs) = maybeLast xs >
It may or may not be expected but it may also be written as: maybeLast' [] = Nothing maybeLast' (x:xs) = Just (fromMaybe x (maybeLast xs)) The main differences are: maybeLast (x:_|_) = _|_ maybeLast' (x:_|_) = Just _|_ maybeLast (fix (x:)) = _|_ maybeLast' (fix (x:)) = Just _|_ Regards
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