September 2017 Update

Task/Align-columns/Haskell/align-columns-2.hs

@@ -0,0 +1,35 @@
+import Prelude as P
+import Data.Text as T
+       (Text, pack, unpack, splitOn, unlines, unwords, length,
+        justifyLeft, justifyRight, center)
+import Data.List (transpose, zip, maximumBy)
+import Data.Ord (comparing)
+
+rows :: [[Text]]
+rows =
+  (splitOn (pack "$") . pack) <$>
+  [ "Given$a$text$file$of$many$lines,$where$fields$within$a$line$"
+  , "are$delineated$by$a$single$'dollar'$character,$write$a$program"
+  , "that$aligns$each$column$of$fields$by$ensuring$that$words$in$each$"
+  , "column$are$separated$by$at$least$one$space."
+  , "Further,$allow$for$each$word$in$a$column$to$be$either$left$"
+  , "justified,$right$justified,$or$center$justified$within$its$column."
+  ]
+
+cols :: [[Text]]
+cols =
+  transpose $
+  ((++) <*>
+   (flip P.replicate (pack []) .
+    (-) (maximum (P.length <$> rows)) . P.length)) <$>
+  rows
+
+main :: IO ()
+main =
+  mapM_ putStrLn $
+  [ (\cols f ->
+        (unpack . T.unlines) $
+        T.unwords <$> transpose ((\(xs, n) -> f (n + 1) ' ' <$> xs) <$> cols))
+      (zip cols ((T.length . maximumBy (comparing T.length)) <$> cols))
+  ] <*>
+  [justifyLeft, justifyRight, center]