2016 Update

Task/CSV-data-manipulation/Haskell/csv-data-manipulation-2.hs

@@ -0,0 +1,49 @@
+{-# LANGUAGE FlexibleContexts,
+             TypeFamilies,
+             NoMonomorphismRestriction #-}
+import Data.List (intercalate)
+import Data.List.Split (splitOn)
+import Lens.Micro
+
+(<$$>) :: (Functor f1, Functor f2) =>
+          (a -> b) -> f1 (f2 a) -> f1 (f2 b)
+(<$$>) = fmap . fmap
+
+------------------------------------------------------------
+-- reading and writing
+
+newtype CSV = CSV { values :: [[String]] }
+
+readCSV :: String -> CSV
+readCSV = CSV . (splitOn "," <$$> lines)
+
+instance Show CSV where
+  show = unlines . map (intercalate ",") . values
+
+------------------------------------------------------------
+-- construction and combination
+
+mkColumn, mkRow :: [String] -> CSV
+(<||>), (<==>) :: CSV -> CSV -> CSV
+
+mkColumn lst = CSV $ sequence [lst]
+mkRow lst    = CSV [lst]
+
+CSV t1 <||> CSV t2 = CSV $ zipWith (++) t1 t2
+CSV t1 <==> CSV t2 = CSV $ t1 ++ t2
+
+------------------------------------------------------------
+-- access and modification via lenses
+
+table = lens values (\csv t -> csv {values = t})
+row i = table . ix i . traverse
+col i = table . traverse . ix i
+item i j = table . ix i . ix j
+
+------------------------------------------------------------
+
+sample = readCSV "C1, C2, C3, C4, C5\n\
+                 \1,  5,  9,  13, 17\n\
+                 \2,  6,  10, 14, 18\n\
+                 \3,  7,  11, 15, 19\n\
+                 \4,  8,  12, 16, 20"

Task/CSV-data-manipulation/Haskell/csv-data-manipulation-3.hs

@@ -0,0 +1,2 @@
+sampleSum = sample <||> (mkRow ["SUM"] <==> mkColumn sums)
+  where sums = map (show . sum) (read <$$> drop 1 (values sample))