Initial data commit

Task/Multiplication-tables/Haskell/multiplication-tables-1.hs

@@ -0,0 +1,36 @@
+import Data.Maybe (fromMaybe, maybe)
+
+------------------- MULTIPLICATION TABLE -----------------
+
+mulTable :: [Int] -> [[Maybe Int]]
+mulTable xs =
+  (Nothing : labels) :
+  zipWith
+    (:)
+    labels
+    [[upperMul x y | y <- xs] | x <- xs]
+  where
+    labels = Just <$> xs
+    upperMul x y
+      | x > y = Nothing
+      | otherwise = Just (x * y)
+
+
+--------------------------- TEST -------------------------
+main :: IO ()
+main =
+  putStrLn . unlines $
+    showTable . mulTable
+      <$> [ [13 .. 20],
+            [1 .. 12],
+            [95 .. 100]
+          ]
+
+------------------------ FORMATTING ----------------------
+showTable :: [[Maybe Int]] -> String
+showTable xs = unlines $ head rows : [] : tail rows
+  where
+    w = succ $ (length . show) (fromMaybe 0 $ (last . last) xs)
+    gap = replicate w ' '
+    rows = (maybe gap (rjust w ' ' . show) =<<) <$> xs
+    rjust n c = (drop . length) <*> (replicate n c <>)

Task/Multiplication-tables/Haskell/multiplication-tables-2.hs

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+import Data.List (groupBy)
+import Data.Function (on)
+import Control.Monad (join)
+
+main :: IO ()
+main =
+  mapM_ print $
+  fmap (uncurry (*)) <$>
+  groupBy
+    (on (==) fst)
+    (filter (uncurry (>=)) $ join ((<*>) . fmap (,)) [1 .. 12])