CommonWords.hs

module Main where

import Data.Set (fromList, toList, intersection)
import Data.Char (toLower)

fileToWords fileName = do
  fileText <- readFile fileName
  return $ (fromList . words) (map toLower fileText)
  
commonWords file1 file2 = do  
  words1 <- fileToWords file1
  words2 <- fileToWords file2
  return $  toList $ intersection words1 words2

commonWords2 file1 file2 =
  fileToWords file1 >>= \f1 ->
  fileToWords file2 >>= \f2 ->
  return $  toList $ intersection f1 f2
                                                            
commonWords3 file1 file2 =
  (\f1 f2 -> toList $ intersection f1 f2)
    <$> fileToWords file1
    <*> fileToWords file2
    
main = do
  cw <- commonWords "text1.txt" "text2.txt"
  print cw
  cw2 <- commonWords2 "text1.txt" "text2.txt"
  print cw2
  cw3 <- commonWords3 "text1.txt" "text2.txt"
  print cw3