Data commit

Task/Base64-decode-data/Haskell/base64-decode-data-1.hs

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+--Decodes Base64 to ASCII
+import qualified Data.Map.Strict as Map (Map, lookup, fromList)
+import Data.Maybe (fromJust, listToMaybe, mapMaybe)
+import Numeric (readInt, showIntAtBase)
+import Data.Char (chr, digitToInt)
+import Data.List.Split (chunksOf)
+
+byteToASCII :: String -> String
+byteToASCII = map chr . decoder
+
+--generates list of bytes (represented by Int)
+decoder :: String -> [Int]
+decoder =
+  map readBin .
+  takeWhile (\x -> length x == 8) .
+  chunksOf 8 . concatMap toBin . mapMaybe (`Map.lookup` table) . filter (/= '=')
+
+--turns decimal into a list of char that represents a binary number
+toBin :: Int -> String
+toBin n = leftPad $ showIntAtBase 2 ("01" !!) n ""
+
+--this adds all the zeros to the left that showIntAtBase omitted
+leftPad :: String -> String
+leftPad a = replicate (6 - length a) '0' ++ a
+
+--turns list of '0' and '1' into list of 0 and 1
+readBin :: String -> Int
+readBin = fromJust . fmap fst . listToMaybe . readInt 2 (`elem` "01") digitToInt
+
+--lookup list for the sextets
+table :: Map.Map Char Int
+table =
+  Map.fromList $
+  zip "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" [0 ..]
+
+main :: IO ()
+main =
+  putStrLn $
+  byteToASCII
+    "VG8gZXJyIGlzIGh1bWFuLCBidXQgdG8gcmVhbGx5IGZvdWwgdGhpbmdzIHVwIHlvdSBuZWVkIGEgY29tcHV0ZXIuCi0tIFBhdWwgUi4gRWhybGljaA=="

Task/Base64-decode-data/Haskell/base64-decode-data-2.hs

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+{-# LANGUAGE OverloadedStrings #-}
+
+import qualified Data.ByteString.Base64 as Base64 (decode, encode)
+import qualified Data.ByteString.Char8 as B (putStrLn)
+
+main :: IO ()
+main = do
+  B.putStrLn $
+    Base64.encode
+      "To err is human, but to really foul things up you need a computer.\n-- Paul R. Ehrlich"
+  B.putStrLn "\n-->\n"
+  either print B.putStrLn $
+    Base64.decode
+      "VG8gZXJyIGlzIGh1bWFuLCBidXQgdG8gcmVhbGx5IGZvdWwgdGhpbmdzIHVwIHlvdSBuZWVkIGEgY29tcHV0ZXIuCi0tIFBhdWwgUi4gRWhybGljaA=="