Простая задача из раздела C++: удалить те элементы списка, значение которых меньше числа их вхождений в список

task :: [Int] -> [Int]
task x = map fst $ filter (\ z -> (snd z) > (fst z)) (map (\ y -> (y , count y x)) x)
         where count p = foldl (\ acc y -> if (y==p) then acc+1 else acc) 0

task:: [Int] -> [Int] 
task x = let f= map head $ filter (\v -> head v >= length v) $ group $ sort x
         in filter (`elem` f) x

task l = filter (flip elem s) l where s = map fst.filter(\(x,l)->x>=l).map(\x->(head x, length x)).group.sort $ l

import Prelude hiding (lookup)  
import Data.Map hiding (foldl,filter)
 
task :: (Num a, Ord a) => [a] -> [a]
task l = foldl (\acc (i,n) ->
    if i > n then acc else filter (/=i) acc
    ) l (calculate l)
 
calculate :: (Ord element, Num numberOfElements) => 
    [element] -> [(element, numberOfElements)]
calculate = toList.foldl (\acc x ->
    case x`lookup`acc of
        Nothing -> insert x 1 acc
        Just i  -> insert x (i + 1) acc
    ) empty

import qualified Data.Map as M

import qualified Data.IntMap as IM
 
task :: [Int] -> [Int]
task lst = filter (`IM.notMember` del lst) lst
  where del = IM.filterWithKey (<) . foldr (\x -> IM.insertWith (+) x 1) IM.empty

task :: [Int] -> [Int]
task x = map fst $ filter (\ z -> (fst z) >= (snd z)) (map (\ y -> (y , count y x)) x)
         where count p = foldl (\ acc y -> if (y==p) then acc+1 else acc) 0
 
Main> task [1,2,3,1,2,3,1,2,3,4]
[3,3,3,4]
Main> task [1,2,3,1,2,3,1,2,3,4,4,4,4,4,4]
[]
Main> task [2,3,1,2,3,2,3,4,4,4,4,4,4]
[]
Main> task [2,3,3,4,4,4,4,4,4]
[2,3,3]      
Main> task [2,2,3,3,4,4,4,4,4,4]
[2,2,3,3]
Main> task [2,2,2,3,3,4,4,4,4,4,4]
[3,3]