mates.
I need help with the following code in haskell which is a basic calculator with a basic user interface, however I still can’t get it to run let alone allow me to do the operations that in theory it should do. Can anyone help me by giving me some guidance or telling me where the code is wrong or if it needs anything else? The code:

import System.IO
import Text.ParserCombinators.Parsec
import Text.ParserCombinators.Parsec.Expr
import Control.Monad

-- Definiciones de parser

expr :: Parser Int
expr = term `chainl1` addop

term :: Parser Int
term = factor `chainl1` mulop

factor :: Parser Int
factor = try (parens expr) <|> integer

addop, mulop :: Parser (Int -> Int -> Int)
addop = (char '+' >> return (+)) <|> (char '-' >> return (-))
mulop = (char '*' >> return (*)) <|> (char '/' >> return div)

parens :: Parser a -> Parser a
parens p = do
  char '('
  x <- p
  char ')'
  return x

integer :: Parser Int
integer = do
  x <- many1 digit
  return (read x)

-- Definiciones de la interfaz de usuario

box :: [String]
box = [ "+---------------+"
      , "|               |"
      , "+---+---+---+---+"
      , "| q | c | d | = |"
      , "+---+---+---+---+"
      , "| 1 | 2 | 3 | + |"
      , "+---+---+---+---+"
      , "| 4 | 5 | 6 | - |"
      , "+---+---+---+---+"
      , "| 7 | 8 | 9 | * |"
      , "+---+---+---+---+"
      , "| 0 | ( | ) | / |"
      , "+---+---+---+---+"
      ]

buttons :: [Char]
buttons = "qcd=123+456-789*0()/"

-- Funciones de la interfaz de usuario

display :: String -> IO ()
display xs = do
  cls
  showbox
  goto (3, 2)
  putStr xs

getCh :: IO Char
getCh = do
  hSetEcho stdin False
  c <- getChar
  hSetEcho stdin True
  return c

calc :: String -> IO ()
calc xs = do
  display xs
  c <- getCh
  if elem c buttons
    then process c xs
    else do
      beep
      calc xs

process :: Char -> String -> IO ()
process c xs
  | elem c "qQESC" = quit
  | elem c "dDBSDEL" = delete xs
  | elem c "=n" = eval xs
  | elem c "cC" = clear
  | otherwise = press c xs

quit :: IO ()
quit = goto (1, 14)

delete :: String -> IO ()
delete "" = calc ""
delete xs = calc (init xs)

eval :: String -> IO ()
eval xs = case parse expr "" xs of
  Left _ -> do
    beep
    calc xs
  Right n -> calc (show n)

clear :: IO ()
clear = calc ""

press :: Char -> String -> IO ()
press c xs = calc (xs ++ [c])

-- Funciones auxiliares para la interfaz de usuario

cls :: IO ()
cls = putStr "ESC[2J"

goto :: (Int,Int) -> IO ()
goto (x,y) = putStr ("ESC[" ++ show y ++ ";" ++ show x ++ "H")

showbox :: IO ()
showbox = mapM_ ((y, xs) -> writeat (1, y) xs) (zip [1..13] box)

writeat :: (Int,Int) -> String -> IO ()
writeat (x,y) xs = do
  goto (x,y)
  putStr xs

beep :: IO ()
beep = putStr "BEL"

-- Función principal para ejecutar la calculadora

run :: IO ()
run = do
  cls
  showbox
  clear
  
main :: IO ()
main = run

I have tried mofidicating the libraries and functions, but to no avail.
I need help with the code 🙁