gistfile1.hs

module Main where

import Control.Monad(join)



table = [(1, "a", "b"), 
         (0, "c", "d"), 
         (2, "e", "f")]



query = do (x,y,z) <- table
           join $ if x<1 then return [x]
                         else return [x, -x]

query1 = do
    (x,y,z) <- table
    if x<1 then [x] else [x, -x]


main = do print query
          print query1