-- Client that uses the Stack ADT
module StackClient where

import Stack

s1 = push 3 (push 4 empty)

exGood = pop s1

-- isEmptyBad :: Stack a -> Bool
-- isEmptyBad s = case s of
--     MkStack [] -> True
--     _          -> False

isEmpty :: Stack a -> Bool
isEmpty s = case pop s of
    Nothing -> True
    _       -> False