{-
This program works.  It returns a nice 500 Server Error result if there are any SQL errors (e.g., an invalid DSN).

But I want proc to return a CGIResult, not a String.  So I can use output, or redirect, or whatever else from inside proc.

I tried changing proc to:
proc :: DB.Connection -> CGI.CGI CGI.CGIResult

Then I tried putting 'lift' in all sorts of places in cgiMain.  But I can't figure out how to make it work.  Any hope for me?
-}

import qualified Control.Exception as Exception (bracket)
import qualified Database.HDBC as DB
import qualified Database.HDBC.ODBC as ODBC
import qualified List
import Control.Monad.Trans (lift)
import qualified Network.NewCGI as CGI
import Text.XHtml
import qualified System
import qualified System.IO.Error as IOE

cgiMain :: CGI.CGI CGI.CGIResult
cgiMain =
	do
	res <- lift $ DB.handleSqlError $ Exception.bracket
		(ODBC.connectODBC "DSN=lbugs")
		DB.disconnect
		proc
	CGI.output res

proc :: DB.Connection -> IO String
proc dbh =
	do
	args <- System.getArgs
	return (join " " ["Hello World!", (join ", " args)])

main :: IO ()
main = CGI.runCGI (CGI.handleErrors cgiMain)

join :: [a] -> [[a]] -> [a]
join sep = concat . List.intersperse sep