[Haskell-cafe] Instance classes and error (also, related to Data.Binary.GET)

Brandon S. Allbery KF8NH allbery at ece.cmu.edu
Thu Jan 3 20:23:30 EST 2008

On Jan 3, 2008, at 18:13 , bbrown wrote:

> DbReader.hs:119:22:
>     No instance for (Binary (Get URLInfo))
>       arising from a use of `decode' at DbReader.hs:119:22-45

Without looking more closely, this suggests to me that you have  
mismatched or incorrectly encapsulated monads (for example, treating  
a value in the Get monad as if it were pure).  This might be related  
to the way you specify the types of the values obtained from decode.

(I haven't used Data.Binary.)

brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allbery at kf8nh.com
system administrator [openafs,heimdal,too many hats] allbery at ece.cmu.edu
electrical and computer engineering, carnegie mellon university    KF8NH

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