Don't trust serializer, they have nothing todo with a reasonable binary encoding

Hufflepdf.cabal

@@ -30,8 +30,8 @@ library
                      , base >=4.9 && <4.13
                      , bytestring
                      , containers
-                     , data-serializer
                      , mtl
+                     , utf8-string
   hs-source-dirs:      src
   ghc-options:         -Wall
   default-language:    Haskell2010

src/PDF/Object.hs

@@ -34,8 +34,8 @@ module PDF.Object (
 
 import Control.Applicative ((<|>), many)
 import Data.Attoparsec.ByteString.Char8 (choice, count, option, sepBy)
-import Data.ByteString (ByteString)
-import qualified Data.ByteString as BS (
+import Data.ByteString.Char8 (ByteString)
+import qualified Data.ByteString.Char8 as BS (
     concat, cons, pack, singleton, unpack
   )
 import Data.Map (Map, (!), mapWithKey)

src/PDF/Text.hs

@@ -15,6 +15,7 @@ import Control.Monad.State (put)
 import Data.Attoparsec.ByteString.Char8 (choice, count, parseOnly, sepBy)
 import qualified Data.Attoparsec.ByteString.Char8 as Atto (Parser)
 import Data.ByteString.Char8 (ByteString, pack)
+import qualified Data.ByteString.UTF8 as UTF8 (toString)
 import Data.Map (Map, (!))
 import qualified Data.Map as Map (empty, fromList)
 import PDF.Object (
@@ -55,20 +56,28 @@ cMapChar = do
       <$> (stringObject <* blank) <*> (stringObject <* blank) <* EOL.parser
 
 mapFromTo (Hexadecimal from) (Hexadecimal to) (StringObject (Hexadecimal dstFrom)) =
-  undefined
+  let dstFrom
 mapFromTo (Hexadecimal from) (Hexadecimal to) (Array dstPoints) = undefined
-mapFromTo _ _ _ = Map.empty
+mapFromTo _ _ _ = fail "invalid range mapping found"
 
 pairMapping :: StringObject -> StringObject -> (Int, ByteString)
 pairMapping (Hexadecimal from) (Hexadecimal to) =
-  (read $ "0x" ++ from, 
+  (hexString from, toByteString to)
+pairMapping = fail "invalid pair mapping found"
 
-fromBytes :: String -> ByteString
-fromBytes s
+hexString :: Num a => String -> a
+hexString s = read $ "0x" ++ s
+
+toByteString :: String -> [Word8]
+toByteString = pack . toBaseWord8 [] . hexString
   where
-    toBaseWord8 n
-      | n < 0xff = [
-    to
+    toBaseWord8 digits n
+      | n < 0xff = (fromIntegral n):digits
+      | otherwise =
+        let newDigits = (fromIntegral (n `mod` 0xff)):digits in
+        case n `div` 0xff of
+          0 -> newDigits
+          k -> toBaseWord8 newDigits k
 
 data StateOperator =
   Cm | W | J | J_ | M | D | Ri | I | Gs -- general graphic state