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

"José A. Lopes" jose.lopes at ist.utl.pt
Tue Oct 23 23:03:28 CEST 2012

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!


José António Branquinho de Oliveira Lopes
Instituto Superior Técnico
Technical University of Lisbon

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