Hi,
instead of writing a function getTransaction that retrieves the
connection you could write a function withConnection that doesn't return
the connection itself but performs an operation on the connection:
withConnection ::
(forall c. Connection c => c -> Transaction a) -> Transaction a
withConnection f = Transaction (\t@(TransactionT c) ->
let Transaction tf = f c in tf t)
Then execute becomes:
execute :: String -> Transaction ()
execute s = withConnection (\c -> connectionExecute c s)
Regards,
Martin.
getConnection :: Transaction c
getConnection = Transaction (\t@(TransactionT c) -> (c, t))
class Connection c where
connectionExecute :: c -> String -> Transaction ()
execute :: String -> Transaction ()
execute s = connectionExecute getConnection s
_______________________________________________
Haskell-Cafe mailing list
[email protected]
http://www.haskell.org/mailman/listinfo/haskell-cafe
