Deque.hs

module Deque (Deque (First, Bottom), addFirst, addLast) where
import Prelude hiding (print)

data Deque a  = First a (Deque a)
              | Bottom
              
              
print :: (Show a)=> Deque a -> String
print Bottom = "Prazdny"    
print (First f Bottom) = (show f)     
print (First f d) = (show f) ++ "<=>" ++ print d     
print Bottom = "Prazdny"    

instance (Show a)=> Show (Deque a) where
    show d = print d
              
addFirst :: a -> Deque a -> Deque a
addFirst x s = First x s

addLast :: a -> Deque a -> Deque a
addLast x (First e f) = First e (addLast x f)
addLast x (Bottom) = (First x Bottom)

Stack.hs

module Stack (Stack (Element, Bottom), push, pop, top, isEmpty) where
import Prelude

data Stack a  = Element a (Stack a)
              | Bottom
            
              
push :: a -> Stack a -> Stack a
push x s = Element x s


pop :: Stack a -> Stack a
pop (Bottom) = error "Stack underrun"
pop (Element x s) = s

instance (Show a)=> Show (Stack a) where
    show (Bottom) = "Prazdny"
    show (Element e (Bottom)) = show e
    show (Element e x) = show e ++ "->" ++ (show x) 
 
top :: Stack a -> a
top (Bottom) = error "aaa"
top (Element x s) = x

isEmpty :: Stack a ->Bool
isEmpty (Bottom) = True
isEmpty (x) = False