Xah Lee <xah...@gmail.com> wrote: > here's a interesting toy list processing problem. > > I have a list of lists, where each sublist is labelled by a number. I > need to collect together the contents of all sublists sharing the same > label. So if I have the list > > ((0 a b) (1 c d) (2 e f) (3 g h) (1 i j) (2 k l) (4 m n) (2 o p) (4 q > r) (5 s t)) > > where the first element of each sublist is the label, I need to > produce: > > output: > ((a b) (c d i j) (e f k l o p) (g h) (m n q r) (s t)) > > [...] > > anyone care to give a solution in Python, Perl, javascript, or other > lang? am guessing the scheme solution can be much improved... perhaps > using some lib but that seems to show scheme is pretty weak if the lib > is non-standard.
In Haskell the solution looks like this: import qualified Data.Map as M import qualified Data.Set as S import Data.Map (Map) import Data.Set (Set) collect :: (Ord a, Ord k) => [Map k (Set a)] -> Map k (Set a) collect = M.unionsWith S.union Greets, Ertugrul -- nightmare = unsafePerformIO (getWrongWife >>= sex) http://ertes.de/ -- http://mail.python.org/mailman/listinfo/python-list
