2023_12_20.hs

-- 1) Define a "generalized" zip function which takes a finite list of possibly infinite lists, and returns a possibly infinite list containing a list of all the first elements, followed by a list of all the second elements,
-- and so on.
-- E.g. gzip [[1,2,3],[4,5,6],[7,8,9,10]] ==> [[1,4,7],[2,5,8],[3,6,9]]
-- 2) Given an input like in 1), define a function which returns the possibly infinite list of the sum of the two greatest elements in the same positions of the lists.
-- E.g. sum_two_greatest [[1,8,3],[4,5,6],[7,8,9],[10,2,3]] ==> [17,16,15]

-- gzip :: [[a]] -> [[a]]

help :: [[a]] -> [[a]]
help l = map (\pos -> map (\ls -> ls !! pos) l) sizeList
  where
    sizeList = [0 .. (foldr min (length (head l)) (map length (tail l)))]

help' l = map (\pos -> map (\ls -> ls !! pos) l) sizeList
  where
    sizeList = [0 .. (foldr min Infinity (map length l))]

gzip xs =
  if null
    (filter null xs)
    then (map head xs) : gzip (map tail xs)
    else []

-- gziph (x : y : xs) = gziph [zipL x y, xs]
--   where
--     zipL x y = fmap (\(a, b) -> [a, b]) (zip x y)

-- [ [[1,4],[2,5],[3,6]], [7, 8, 9] ]
-- [ [[1,4], 7], [[2,5], 8], [[3,6], 9]]

-- gzip' l = foldl (\(x, z) -> ) [] l