[Haskell-cafe] Help: Main: thread blocked in MVar operation

Hey everyone, I changed my code I now I get the following error message Main: thread blocked indefinitely in an MVar operation Before the change, I was using the State monad with runState. Then, I changed the code to use the StateT monad transformer wrapped around IO monad and runStateT. And this change introduced the error message. BTW I am using DoRec extension, maybe it is the source of the problem, but I don't know. Here are some specs: ghc 7.4.2 mtl 2.1.1 If you need any other information please don't hesitate to ask. Any help is greatly appreciated! Cheers, José -- José António Branquinho de Oliveira Lopes Instituto Superior Técnico Technical University of Lisbon