Data commit

Task/Binary-digits/Haskell/binary-digits-1.hs

@@ -0,0 +1,27 @@
+import Data.List
+import Numeric
+import Text.Printf
+
+-- Use the built-in function showBin.
+toBin n = showBin n ""
+
+-- Use the built-in function showIntAtBase.
+toBin n = showIntAtBase 2 ("01" !!) n ""
+
+-- Implement our own version.
+toBin1 0 = []
+toBin1 x =  (toBin1 $ x `div` 2) ++ (show $ x `mod` 2)
+
+-- Or even more efficient (due to fusion) and universal implementation
+toBin2 = foldMap show . reverse . toBase 2
+
+toBase base = unfoldr modDiv
+  where modDiv 0 = Nothing
+        modDiv n = let (q, r) = (n `divMod` base) in Just (r, q)
+
+
+printToBin n = putStrLn $ printf "%4d  %14s  %14s" n (toBin n) (toBin1 n)
+
+main = do
+  putStrLn $ printf "%4s  %14s  %14s" "N" "toBin" "toBin1"
+  mapM_ printToBin [5, 50, 9000]

Task/Binary-digits/Haskell/binary-digits-2.hs

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+import Data.Bifunctor (first)
+import Data.List (unfoldr)
+import Data.Tuple (swap)
+
+---------------------- BINARY DIGITS ---------------------
+
+binaryDigits :: Int -> String
+binaryDigits = reverse . unfoldr go
+  where
+    go 0 = Nothing
+    go n = Just . first ("01" !!) . swap . quotRem n $ 2
+
+
+--------------------------- TEST -------------------------
+main :: IO ()
+main =
+  mapM_
+    ( putStrLn
+        . ( ((<>) . (<> " -> ") . show)
+              <*> binaryDigits
+          )
+    )
+    [5, 50, 9000]