You haven&#39;t really said what happens when you try this, but I would bet that things would be clarified greatly if you put type signatures on your two definitions. <br><br><div class="gmail_quote">On Fri, Apr 3, 2009 at 12:49 PM, Michael Roth <span dir="ltr">&lt;<a href="mailto:mroth@nessie.de">mroth@nessie.de</a>&gt;</span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">Hello list,<br>
<br>
maybe I&#39;m just stupid, I&#39;m trying to do something like this:<br>
<br>
<br>
        import Control.Monad<br>
        import Control.Monad.Trans<br>
        import Control.Monad.List<br>
<br>
        foobar = do<br>
                a &lt;- [1,2,3]<br>
                b &lt;- [4,5,6]<br>
                liftIO $ putStrLn $ (show a) ++ &quot; &quot; ++ (show b)<br>
                return (a+b)<br>
<br>
        main = do<br>
                sums &lt;- foobar<br>
                print sums<br>
<br>
<br>
But this apparently doesn&#39;t work... I&#39;m total clueless how<br>
to achieve the correct solution. Maybe my mental image<br>
on the monad transformer thing is totally wrong?<br>
<br>
<br>
Michael<br>
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</blockquote></div><br>