Извлечение ключа из имени файла

lab3/src/Lib.hs

@@ -11,6 +11,7 @@ module Lib
 
 import Codec.Picture
 
+import Text.Read (readMaybe)
 import Data.Word (Word8)
 import Data.Char (ord, chr)
 import Data.Bits (testBit, shiftL, complement, (.|.), (.&.))
@@ -112,4 +113,9 @@ extractBitsFromImage bitsPerByte img =
     let width = imageWidth img
         height = imageHeight img
         pixels = [ pixelAt img x y | y <- [0..height - 1], x <- [0..width - 1] ]
-    in concatMap (extractBitsFromPixel bitsPerByte) pixels
+    in concatMap (extractBitsFromPixel bitsPerByte) pixels
+
+extractShift :: String -> Maybe Int
+extractShift path = 
+    let prefix = takeWhile (`elem` ['0'..'9']) (reverse $ takeWhile (/= '_') (reverse path))
+    in readMaybe (reverse prefix)