At last..<br><br>No, it wants me to define an instance for<br>(StateT s) which is supposed to be defined<br>be the authors of the library.<br><br>Actually I discovered that I have two libraries<br>called transformers. <br>
<br> transformers-0.2.2.0<br>
transformers-0.3.0.0<br><br>So when I'm doing <br><br>import Control.Monad.Trans (0.2.2.0)<br><br>I get the error<br><br>And when I'm doing<br><br>import Control.Monad.Trans.Class (0.2.2.0)<br><br>It compiles.<br>
<br><br>Anton<br><br>