content: -- BSort.hs
  -- Copyright (C) 2012 Liu Xinyu (liuxinyu95@gmail.com)
  -- 
  -- This program is free software: you can redistribute it and/or modify
  -- it under the terms of the GNU General Public License as published by
  -- the Free Software Foundation, either version 3 of the License, or
  -- (at your option) any later version.
  -- 
  -- This program is distributed in the hope that it will be useful,
  -- but WITHOUT ANY WARRANTY; without even the implied warranty of
  -- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  -- GNU General Public License for more details.
  -- 
  -- You should have received a copy of the GNU General Public License
  -- along with this program.  If not, see <http://www.gnu.org/licenses/>.
  
  -- Bubble Sort
  module BSort where
  
  import Test.QuickCheck
  import qualified Data.List as L
  
  pass [] = (True, [])
  pass [x] = (True, [x])
  pass (x:y:xs) | x <= y    = let (o, xs') = pass (y:xs) in (o, x:xs')
                | otherwise = let (_, xs') = pass (x:xs) in (False, y:xs')
  
  bsort xs = let (o, xs') = pass xs in
             if o then xs' else bsort xs'
  
  prop_sort :: (Ord a, Num a) => [a] -> Bool
  prop_sort xs = L.sort xs == bsort xs
  