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

["José A. Lopes"]

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