propBuyQtyMatch :: OrderBuy -> Book -> Bool
propBuyQtyMatch buy book = bookLiquidity book + bSize buy - (2 * sum (map tradeSize trades)) == bookLiquidity newBook
  where (newBook, trades) = processBuy book buy
propBuyQtyMatch :: OrderBuy -> Book -> Bool
propBuyQtyMatch buy book = bookLiquidity book + bSize buy - (2 * sum (map tradeSize trades)) == bookLiquidity newBook
  where (newBook, trades) = processBuy book buy
propBuyQtyMatch buy book = bookLiquidity book + bSize buy - (2 * sum (map tradeSize trades)) == bookLiquidity newBook
  where (newBook, trades) = processBuy book buy