Динамическое извлечение алфавита

lab3/app/Main.hs

@@ -3,4 +3,7 @@ module Main (main) where
 import Lib
 
 main :: IO ()
-main = someFunc
+main = do
+    inputText <- readFile "resources/biography.txt"
+    putStrLn $ take 30 inputText
+    putStrLn $ createAlphabetFromText inputText

lab3/src/Lib.hs

@@ -1,6 +1,12 @@
 module Lib
-    ( someFunc
+    ( 
+        createAlphabetFromText
     ) where
 
-someFunc :: IO ()
-someFunc = putStrLn "someFunc"
+createAlphabetFromText :: String -> [Char]
+createAlphabetFromText [] = []
+createAlphabetFromText (x:xs)
+    | x `elem` alphabet = alphabet
+    | otherwise     = x : alphabet
+  where
+    alphabet = createAlphabetFromText xs