Re: [Haskell-beginners] confused by <-

Ignore my message. I think I'm looking at the wrong version of simpleHttp or something. I should have tried it in ghci before I posted. On Thu, Sep 27, 2012 at 1:43 PM, David McBride wrote:

I think what he is asking is if try (from lifted) has type

try :: (MonadBaseControlhttp://hackage.haskell.org/packages/archive/monad-control/0.3.1.4/doc/html/C... IOhttp://hackage.haskell.org/packages/archive/base/4.5.0.0/doc/html/System-IO....m, Exceptionhttp://hackage.haskell.org/packages/archive/base/4.5.0.0/doc/html/Control-Ex...e) => m a -> m ( Eitherhttp://hackage.haskell.org/packages/archive/base/4.5.0.0/doc/html/Data-Eithe...e a)

and simpleHttp is

simpleHttp "googe" :: IOhttp://hackage.haskell.org/packages/archive/base/4.6.0.0/doc/html/System-IO....( Resulthttp://hackage.haskell.org/packages/archive/HTTP/latest/doc/html/Network-Str...( Responsehttp://hackage.haskell.org/packages/archive/HTTP/latest/doc/html/Network-HTT...ty))

then how can the whole statement have

try $ simpleHttp "goog" :: GHandler master sub (Either SomeException ByteString)

when the m in both parts of try is the same, it should end up IO not GHandler master sub. So I don't understand why this would work, either.

On Thu, Sep 27, 2012 at 1:33 PM, Brent Yorgey wrote:

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On Thu, Sep 27, 2012 at 10:01:25AM -0700, Bryce Verdier wrote:

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On 9/26/12 6:00 PM, Ertugrul Söylemez wrote:

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Bryce Verdier wrote:

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body <- L.try (simpleHttp "http://www.google.com") :: IO

(Either

...

L.SomeException Data.ByteString.Lazy.Internal.ByteString) Almost right, but your type signature is lying. =)

Greets, Ertugrul

Thanks for your hint, with a fair amount of head bashing against a wall I was able to figure this out. At the end of day I got :

body <- try (simpleHttp "http://www.google.com") :: GHandler PlayHaven PlayHaven (Either SomeException ByteString)

Do you need a type signature there at all?

-Brent

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