Self-describing numbers: Difference between revisions

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@@ Line 791: / Line 791: @@
 isSelfDescribing :: Integer -> Bool
-isSelfDescribing n =
+isSelfDescribing n = nu == f
-    nu == f where
+  where
-            nu = map digitToInt (show n)
+    nu = digitToInt <$> show n
-            f = map (\a -> count a nu) [0 .. ((length nu)-1)]
+    f = (`count` nu) <$> [0 .. length nu - 1]
+main :: IO ()
 main = do
+  print $
-    let tests = [1210, 2020, 21200, 3211000,
+    isSelfDescribing <$>
-                 42101000, 521001000, 6210001000]
+    [1210, 2020, 21200, 3211000, 42101000, 521001000, 6210001000]
-    print $ map isSelfDescribing tests
-    print $ filter isSelfDescribing [0 .. 4000000]</lang>
+  print $ filter isSelfDescribing [0 .. 4000000]</lang>
 Output:
 <pre>[True,True,True,True,True,True,True]