Haskell: A simple database application with takusen + sqlite3

Takusen is a Haskell library to access databases. The easiest way to get takusen by darcs. If you don't have darcs installed, you can learn about it from here. If you don't want to use darcs then you would have to download the tar file and extract it. Instructions to install Takusen can be found here. If you're too lazy to read that here's how would install takusen with darcs:

$ mkdir takusen
$ cd takusen
$ darcs get http://darcs.haskell.org/takusen
$ ghc --make Setup
$ Setup configure
$ Setup build
$ Setup install

Next, we will create a sqlite3 database with a simple table tbl1:

$ mkdir sqlite_demo
$ cd sqlite_demo
$ sqlite3 demo.db
SQLite version 3.5.6
Enter ".help" for instructions
sqlite> create table tbl1 (key TEXT, value TEXT);
sqlite> insert into table tbl1 values('k1', 'v1');
sqlite> insert into table tbl1 values('k2', 'v2');
sqlite> insert into table tbl1 values('k3', 'v3');
sqlite> .quit

Create sqlite_demo.hs and enter this:

{-# OPTIONS -fglasgow-exts #-}
{-# OPTIONS -fallow-overlapping-instances #-}
module Main (main) where
import Database.Sqlite.Enumerator
import Control.Monad.Trans (liftIO)
import System.Environment

query1Iteratee :: (Monad m) => String -> String -> IterAct m [(String, String)]
query1Iteratee a b accum = result' ((a,b):accum)

main :: IO ()
main = do
flip catchDB reportRethrow $
withSession (connect "demo.db") (do
let iter (s::String) (_::String) = result s
result <- doQuery (sql "select * from tbl1") query1Iteratee []      
liftIO $ putStrLn $ show result            
)

Compile with the following command and run:

$ ghc --make sqlite_demo -o sqlite_demo
$ ./sqlite_demo

You should get this:

[("k3","v3"),("k2","v2"),("k1","v1")]