Data commit

Task/Bell-numbers/Haskell/bell-numbers-1.hs

@@ -0,0 +1,16 @@
+bellTri :: [[Integer]]
+bellTri =
+  let f xs = (last xs, xs)
+   in map snd (iterate (f . uncurry (scanl (+))) (1, [1]))
+
+bell :: [Integer]
+bell = map head bellTri
+
+main :: IO ()
+main = do
+  putStrLn "First 10 rows of Bell's Triangle:"
+  mapM_ print (take 10 bellTri)
+  putStrLn "\nFirst 15 Bell numbers:"
+  mapM_ print (take 15 bell)
+  putStrLn "\n50th Bell number:"
+  print (bell !! 49)

Task/Bell-numbers/Haskell/bell-numbers-2.hs

@@ -0,0 +1,4 @@
+import Control.Arrow
+
+bellTri :: [[Integer]]
+bellTri = map snd (iterate ((last &&& id) . uncurry (scanl (+))) (1,[1]))

Task/Bell-numbers/Haskell/bell-numbers-3.hs

@@ -0,0 +1,4 @@
+import Control.Applicative
+
+bellTri :: [[Integer]]
+bellTri = map snd (iterate ((liftA2 (,) last id) . uncurry (scanl (+))) (1,[1]))

Task/Bell-numbers/Haskell/bell-numbers-4.hs

@@ -0,0 +1,2 @@
+bellTri :: [[Integer]]
+bellTri = map snd (iterate (((,) . last <*> id) . uncurry (scanl (+))) (1, [1]))