September 2017 Update

Task/Box-the-compass/Haskell/box-the-compass.hs

@@ -1,25 +1,70 @@
-import Data.Char
-import Data.Maybe
-import Text.Printf
+import Data.Char (toUpper)
 
-dirs = ["N", "NbE", "N-NE", "NEbN", "NE", "NEbE", "E-NE", "EbN",
-        "E", "EbS", "E-SE", "SEbE", "SE", "SEbS", "S-SE", "SbE",
-        "S", "SbW", "S-SW", "SWbS", "SW", "SWbW", "W-SW", "WbS",
-        "W", "WbN", "W-NW", "NWbW", "NW", "NWbN", "N-NW", "NbW"]
+import Data.Maybe (fromMaybe)
 
--- Given an index between 0 and 31 return the corresponding compass point name.
+import Text.Printf (PrintfType, printf)
+
+dirs :: [String]
+dirs =
+  [ "N"
+  , "NbE"
+  , "N-NE"
+  , "NEbN"
+  , "NE"
+  , "NEbE"
+  , "E-NE"
+  , "EbN"
+  , "E"
+  , "EbS"
+  , "E-SE"
+  , "SEbE"
+  , "SE"
+  , "SEbS"
+  , "S-SE"
+  , "SbE"
+  , "S"
+  , "SbW"
+  , "S-SW"
+  , "SWbS"
+  , "SW"
+  , "SWbW"
+  , "W-SW"
+  , "WbS"
+  , "W"
+  , "WbN"
+  , "W-NW"
+  , "NWbW"
+  , "NW"
+  , "NWbN"
+  , "N-NW"
+  , "NbW"
+  ]
+
+-- Index between 0 and 31 ->  the corresponding compass point name.
+pointName :: Int -> String
 pointName = capitalize . concatMap (fromMaybe "?" . fromChar) . (dirs !!)
-  where fromChar c = lookup c [('N', "north"), ('S', "south"), ('E', "east"),
-                               ('W', "west"),  ('b', " by "),  ('-', "-")]
-        capitalize (c:cs) = toUpper c : cs
+  where
+    fromChar c =
+      lookup
+        c
+        [ ('N', "north")
+        , ('S', "south")
+        , ('E', "east")
+        , ('W', "west")
+        , ('b', " by ")
+        , ('-', "-")
+        ]
+    capitalize (c:cs) = toUpper c : cs
 
--- Convert degrees to a compass point index between 0 and 31.
-pointIndex d = (round (d*1000) + 5625) `mod` 360000 `div` 11250
+-- Degrees -> compass point index between 0 and 31.
+pointIndex :: Double -> Int
+pointIndex d = (round (d * 1000) + 5625) `mod` 360000 `div` 11250
 
-printPointName d = let deg = read d :: Double
-                       idx = pointIndex deg
-                   in printf "%2d  %-18s  %6.2f°\n" (idx+1) (pointName idx) deg
+printPointName :: PrintfType t => String -> t
+printPointName d =
+  let deg = read d :: Double
+      idx = pointIndex deg
+  in printf "%2d  %-18s  %6.2f°\n" (idx + 1) (pointName idx) deg
 
-main = do
-  input <- getContents
-  mapM_ printPointName $ lines input
+main :: IO ()
+main = mapM_ (printPointName . show) [0 .. 31]