Re: [Haskell-beginners] confused by <-

On 9/26/12 4:53 PM, Ertugrul Söylemez wrote:

Bryce Verdier wrote:

...

This is the new code that is trying to use try (imported from Control.Exception) getGoogR = do body <- try {- [...] -}

[...]

I'm sure that my problem has a simple fix, but I just don't know what it is. I will be happy to share any other code if people ask, I'm just giving the short version for brevities sake. The fix is indeed simple. In fact you're just using the wrong 'try', because Yesod handlers aren't IO actions, but actions in a monad that is specific to your application, called Handler. The error message suggests that, although the type is spelled out completely there.

What you want is the lifted version of 'try', which you find in the Control.Exception.Lifted module.

Greets, Ertugrul

Thank you for the reply Ertugrul, sadly that didn't seem to help. :( Here are my changes: import qualified Control.Exception.Lifted as L ... body <- L.try (simpleHttp "http://www.google.com") :: IO (Either L.SomeException Data.ByteString.Lazy.Internal.ByteString) I did the full qualified because the first time I tried your suggestion I just "Control.Exception.Lifted" and I got the same error as I'm sharing below. playhaven.hs:51:19: Couldn't match expected type `IO b0' with actual type `GHandler sub0 master0 RepJson' In the expression: Thanks for being willing to help me with this. Bryce

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