-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 An other approach is to just write the monad you want your self. If you understand monads it's not very difficult (just a few lines). It gives you exactly the monad you want without all the complicated abstraction. And error messages should be very easy to understand. silvio -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iQIcBAEBAgAGBQJP3s9EAAoJEDLsP+zrbatWUBIP/iWp4AUox1T+CkjaqOEi5qa8 YrJxK0STTjOMNtEA2IWBNHTt2WILKBIMUq6KbEL2o5uZBaWgloYobeyYHmQ8L9Tz RkKGwR8+oy8k13xwZm3AQ66b7EPR62LvxYfDTzAsKrg0I0bBS9fCz0u9yS+COGb3 ZMjT2AZpy6S/Acy+vT2AixE0+okQwUgaz64sv0oQw7g/0lOBIVDONQUlpDO6WntI Cbcv5pgr5CsieJvwzr8qU14vHVyFcHm72PWEB+8ZNmIBNWk2l6pA2OoXl2+ILLD1 UnXKJZUWZD/WghibcMZSyFzIs9ID/IObBAF3C3XZBkJb+BukkjE+wyWhuPuYJIcB XqT1GBnhTYmn5wbYVxvH1dIzhVWYODVB6lXoIcX/50bX8ZoXxRa/TnX3L65jhCQZ Rr62i3Z/39jZxa9zLEMc33rr7fB48GTyWjOGUVoJy80G1oUqgqVZGpKOLhzRyZr7 zcyhUc6Q59ooqS/978+Xok1/rIUbi60yhuDQGxjbOlqSbhNfaM1HcSpAQZq9qo/7 uQNvgaw6XQ3oePzO8T5q9Sa5MqixUh6tXJ2/OBIMgiuDlKPyA4d0mWTdHbCVt9am pELdcMaZ5DknjYomQ9gN7tEu7+zggXmoODkVLLPxzDicW4CjOrmCogWiLcLR3Zhq Qq/ja6SNdjS7s1/oQaMX =2mGs -----END PGP SIGNATURE-----