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copied!<p>First, let me preface this answer by the disclaimer that I've never actually used the Facebook API or the <code>Conduits</code> library, so I'm not sure if this code actually does anything sensible, but by going with just the type information, I think this is what you were trying to do</p> <pre><code>main :: IO () main = withManager $ \manager -> FB.runFacebookT app manager $ do fbAuthUrl <- FB.getUserAccessTokenStep1 url perms liftIO $ print fbAuthUrl argument <- liftIO $ readLn token <- FB.getUserAccessTokenStep2 url [argument] u <- FB.getUser "me" [] (Just token) liftIO $ print (FB.userEmail u) </code></pre> <p>The main pitfall is that <code>main</code> in Haskell must <em>always</em> have the type <code>IO a</code>, but you are trying to use a value of type <code>FacebookT Auth m ()</code> as your <code>main</code>. Your implementation is on the right track, but the <code>runFacebookT</code> and <code>withManager</code> need to be the first thing in the function.</p> <p>Type-wise, the actual do-block has the type <code>FacebookT Auth (ResourceT IO) ()</code>. The <code>runFacebookT</code> function is used to unwrap the <code>FacebookT</code> transformer, resulting in a <code>ResourceT IO ()</code> value, which is in turn processed by <code>withManager</code> to produce a plain old <code>IO ()</code>.</p> <p>One additional problem was that you originally had a <code>readLn</code> in your do-block without <code>liftIO</code>, which was confusing the type-inference. I also added the missing <code>Just</code> to the <code>FB.getUser</code> call.</p>

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