tasks a-s

Task/Non-decimal-radices-Convert/Haskell/non-decimal-radices-convert-1.hs

@@ -0,0 +1,4 @@
+Prelude> Numeric.showIntAtBase 16 Char.intToDigit 42 ""
+"2a"
+Prelude> fst $ head $ Numeric.readInt 16 Char.isHexDigit Char.digitToInt "2a"
+42

Task/Non-decimal-radices-Convert/Haskell/non-decimal-radices-convert-2.hs

@@ -0,0 +1,21 @@
+import Data.List
+import Data.Char
+
+toBase :: Int -> Int -> [Int]
+toBase b v = toBase' [] v where
+  toBase' a 0 = a
+  toBase' a v = toBase' (r:a) q where (q,r) = v `divMod` b
+
+fromBase :: Int -> [Int] -> Int
+fromBase b ds = foldl' (\n k -> n * b + k) 0 ds
+
+toAlphaDigits :: [Int] -> String
+toAlphaDigits = map convert where
+  convert n | n < 10    = chr (n + ord '0')
+            | otherwise = chr (n + ord 'a' - 10)
+
+fromAlphaDigits :: String -> [Int]
+fromAlphaDigits = map convert where
+ convert c | isDigit c = ord c - ord '0'
+           | isUpper c = ord c - ord 'A' + 10
+           | isLower c = ord c - ord 'a' + 10

Task/Non-decimal-radices-Convert/Haskell/non-decimal-radices-convert-3.hs

@@ -0,0 +1,4 @@
+*Main> toAlphaDigits $ toBase 16 $ 42
+"2a"
+*Main> fromBase 16 $ fromAlphaDigits $ "2a"
+42