[Haskell-beginners] Deserializing data with ProtocolBuffers

[Raphael Päbst]

Hey!
I am currently working on a project, where I need to serialize data
with ProtocolBuffers.
I have managed to compile a .proto file and serialize messages with
messagePut. However, when I try to deserialize a ByteString again, I
get the following error:

ambiguous type variable `msg0' in the constraints:
(Text.ProtocolBuffers.WireMessage.Wire msg0) arising from a use of
"messageGet" at...
(Text.ProtocolBuffers.Reflections.ReflectDescriptor msg0) arising from
a use of "messageGet" at ...
Probable fix: add a type signature that fixes these type variables in
the expression "messageGet bs"
in an equation for `IT':  "IT = messageGet bs"

I'm trying to call messageGet from the prompt in ghc. What exactly am
I doing wrong? And how can I fix this?

Many Thanks

Raphael