September 2017 Update

Task/Averages-Arithmetic-mean/Haskell/averages-arithmetic-mean-3.hs

@@ -1,5 +1,19 @@
 {-# LANGUAGE BangPatterns #-}
-import Data.List (foldl')
-mean :: (Real n, Fractional m) => [n] -> m
-mean xs = let (s,l) = foldl' f (0, 0) xs in realToFrac s / l
-  where f (!s,!l) x = (s+x,l+1)
+
+import Data.List (foldl') --'
+
+mean
+  :: (Real n, Fractional m)
+  => [n] -> m
+mean xs =
+  let (s, l) =
+        foldl' --'
+          f
+          (0, 0)
+          xs
+  in realToFrac s / l
+  where
+    f (!s, !l) x = (s + x, l + 1)
+
+main :: IO ()
+main = print $ mean [1 .. 100]