1. 2011-12-22 Re: [Haskell-beginners] error monad and Map lookup haskell-b Henk-Jan van Tuyl 2. 2011-12-22 Re: [Haskell-beginners] error monad and Map lookup haskell-b Daniel Fischer 3. 2011-12-22 Re: [Haskell-beginners] error monad and Map lookup haskell-b Brandon Allbery 4. 2011-12-22 [Haskell-beginners] error monad and Map lookup haskell-b Dennis Raddle