gistfile1.hs

{-# LANGUAGE OverloadedStrings #-}                                                                
                                                                                                  
import Control.Applicative                                                                        
import Control.Monad                                                                              
import Control.Monad.IO.Class (liftIO)                                                            
import Database.PostgreSQL.Simple                                                                 
import Database.PostgreSQL.Simple.FromRow                                                         
import Data.Word                                                                                  
import qualified Data.Text as T                                                                   
                                                                                                  
connInfo = ConnectInfo "localhost" (15432 :: Word16) "schoolobjects" "schoolobjects" "schoolobject
s"                                                                                                
                                                                                                  
data Course = Course { title :: T.Text                                                            
                     , description :: Maybe T.Text                                                
                     , creditid :: Maybe Int                                                      
                     , status :: T.Text                                                           
                     } deriving Show                                                              
                                                                                                  
data Activity = Activity { title :: T.Text                                                        
                         , courseid :: Int                                                        
                         , status :: T.Text                                                       
                         } deriving Show                                                          
                                                                                                  
data CourseActivity = CourseActivity {                                                            
                                                                                                  
instance FromRow Course where                                                                     
  fromRow = Course <$> field <*> field <*> field <*> field                                        
                                                                                                  
instance FromRow Activity where                                                                   
  fromRow = Activity <$> field <*> field <*> field                                                
                                                                                                  
                                                                                                  
                                                                                                  
main :: IO ()                                                                                     
main = do                                                                                         
  conn <- connect connInfo                                                                        
  c <- query_ conn "SELECT c.title,                                                               
                           c.description,                                                         
                           c.creditid,                                                            
                           c.status,                                                              
                           a.title,                                                               
                           a.courseid,                                                            
                           a.status                                                               
                    FROM course c                                                                 
                      JOIN activity a on a.courseid = c.courseid                                  
                    limit 1" :: (IO [(Course, Activity)])                                         
                                                                                                  
  putStrLn $ show c