Data commit

Task/Combinations/Haskell/combinations-1.hs

@@ -0,0 +1,4 @@
+comb :: Int -> [a] -> [[a]]
+comb 0 _      = [[]]
+comb _ []     = []
+comb m (x:xs) = map (x:) (comb (m-1) xs) ++ comb m xs

Task/Combinations/Haskell/combinations-2.hs

@@ -0,0 +1,5 @@
+import Data.List (tails)
+
+comb :: Int -> [a] -> [[a]]
+comb 0 _      = [[]]
+comb m l = [x:ys | x:xs <- tails l, ys <- comb (m-1) xs]

Task/Combinations/Haskell/combinations-3.hs

@@ -0,0 +1 @@
+comb0 m n = comb m [0..n-1]

Task/Combinations/Haskell/combinations-4.hs

@@ -0,0 +1 @@
+comb1 m n = comb m [1..n]

Task/Combinations/Haskell/combinations-5.hs

@@ -0,0 +1,2 @@
+import Data.List (sort, subsequences)
+comb m n = sort . filter ((==m) . length) $ subsequences [0..n-1]

Task/Combinations/Haskell/combinations-6.hs

@@ -0,0 +1 @@
+comb m n = filter ((==m . length) $ filterM (const [True, False]) [0..n-1]

Task/Combinations/Haskell/combinations-7.hs

@@ -0,0 +1,12 @@
+comb :: Int -> [a] -> [[a]]
+comb m xs = combsBySize xs !! m
+  where
+    combsBySize = foldr f ([[]] : repeat [])
+    f x next =
+      zipWith
+        (<>)
+        (fmap (x :) <$> ([] : next))
+        next
+
+main :: IO ()
+main = print $ comb 3 [0 .. 4]