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  1. Practice
  2. Functional Programming
  3. Recursion
  4. Pascal's Triangle
  5. Discussions

Pascal's Triangle

  • strawstack + 2 comments

    UPDATE: Finally, figured out how to print a [[Char]] in the correct format with Haskell...

    -- PRINT with FORMAT    
two :: [Int] -> [String]
two m = map (show) m

three :: [[Int]] -> [[String]]
three m = map (two) m

main = do   
   m <- readLn :: IO Int
   --send (tri m) -- print tri to row m
   mapM_ (putStrLn . intercalate " " $) (three (tri m))

    Where (tri m) produces [["1"], ["1", "1"], ["1", "2", "1"], ["1", "3", "3", "1"]]

    • ende76 + 0 comments

      Thanks for this chain of posts. I was struggling through the same problems with how to properly output.
      Much longer than to solve the actual problem!

    • tury345 + 1 comment

      Achieved something similar here:

      putStr (unlines (map (\line -> unwords (map (\(x:[]) -> show x) line)) rows))

      where rows is [[1], [1, 1], [1, 2, 1], [1, 3, 3, 1]]

      • egoek + 1 comment

        I concocted this:

        mapM_ putStrLn (map (\x -> unwords (map show x)) result)

        where result is [[1], [1, 1], [1, 2, 1] ...] I'm sure I could get rid of the parenthesis. Any suggestions welcome.

        • twostepted + 0 comments

          Nice. Vscode extension 'Haskutil' recommended shorten slightly to this

            n <- readLn
  mapM_ (putStrLn . unwords . map show) $ tri n