simplified functions, ignore non ascii characters

src/Encoding/LetterToNumber.hs

@@ -1,59 +1,30 @@
+
 module Encoding.LetterToNumber
   ( encltn
   , decltn
   ) where 
 
-import Data.Char (ord, chr, isAscii, isAlpha, isSpace, isDigit, toUpper, isLatin1)
-import Data.List (intercalate)
+import Data.Char (ord, chr, isAscii, isAlpha, isSpace, isDigit, toUpper)
 import Data.ByteString (ByteString)
 import qualified Data.ByteString.Char8 as BC
 
+-- This encodes ASCII characters only and ignores all other characters
+
 charToNumber :: Char -> ByteString
 charToNumber c
+  | not (isAscii c) = BC.pack ""
   | isAlpha c = BC.pack $ show $ ord (toUpper c) - ord 'A' + 1
   | isSpace c = BC.pack "0"
   | otherwise = BC.singleton c
-  -- | isAlpha c = show $ ord (toUpper c) - ord 'A' + 1
-  -- | isSpace c = "0"
-  -- -- | isLatin1 c = [c]
-  -- | otherwise = [c]
 
-numberToChar :: String -> Char
+numberToChar :: ByteString -> ByteString
 numberToChar s
-  | s == "0" = ' '
-  | all isDigit s = chr $ read s + ord 'A' -1
-  | otherwise = head s
-  -- | otherwise = chr $ read s + ord 'A' - 1
+  | s == BC.pack "0" = BC.singleton ' '
+  | BC.all isDigit s = BC.singleton $ chr $ (read $ BC.unpack s) + ord 'A' - 1
+  | otherwise = s
 
 encltn :: ByteString -> ByteString
-encltn input = go (BC.unpack input) []
-  where
-    go :: String -> [ByteString] -> ByteString 
-    go [] acc = BC.intercalate (BC.pack "-") (reverse acc)
-    go (x:xs) acc
-      -- | not (isAscii x) = go xs (BC.singleton x : acc)
-      | not (isAscii x) = error "Non-ASCII character detected"
-      | otherwise = go xs (charToNumber x : acc)
--- encltn input = BC.intercalate (BC.pack "-") $ map charToNumber' $  BC.unpack input
---   where
---     charToNumber' c
---       | not (isAscii c)= BC.singleton c
---       | otherwise = charToNumber c
+encltn input = BC.unwords $ filter (not . BC.null) $ map charToNumber $ BC.unpack input
 
 decltn :: ByteString -> ByteString
-decltn input = BC.pack $ concatMap (processSegment .  BC.unpack) $ BC.split '-' input
-  where
-    processSegment :: String -> String
-    processSegment s
-      | all isDigit s = [numberToChar s]
-      | otherwise = s
--- decltn input = BC.pack $ go $ BC.split '-' input
---   where 
---     go :: [ByteString] -> String
---     go [] = []
---     go (x:xs) = 
---       let str = BC.unpack x
---        in numberToChar str ++ go xs
-       -- in case all isDigit str of
-            -- True -> numberToChar str : go xs
-            -- False -> str ++ go xs
+decltn input = BC.concat $ map numberToChar $ BC.words input