Van Eck sequence: Difference between revisions

Content added Content deleted

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@@ Line 1,610: / Line 1,610: @@
 <lang haskell>{-# LANGUAGE TupleSections #-}
-import qualified Data.Map.Strict as M hiding (drop)
 import Data.List (mapAccumL)
+import qualified Data.Map.Strict as M hiding (drop)
 import Data.Maybe (maybe)
+--------------------- VAN ECK SEQUENCE -------------------
 vanEck :: [Int]
@@ Line 1,618: / Line 1,620: @@
   where
     go (x, dct) i =
-      ((,) =<< (, M.insert x i dct)) (maybe 0 (i -) (M.lookup x dct))
+      ((,) =<< (, M.insert x i dct))
+        (maybe 0 (i -) (M.lookup x dct))
+--------------------------- TEST -------------------------
 main :: IO ()
 main =
   mapM_ print $
+    fmap
-  (drop . subtract 10 <*> flip take vanEck) <$>
+      ((drop . subtract 10) <*> flip take vanEck)
-  [10, 1000, 10000, 100000, 1000000]</lang>
+      [10, 1000, 10000, 100000, 1000000]</lang>
 {{Out}}
 <pre>[0,0,1,0,2,0,2,2,1,6]