[Haskell-cafe] Stacking monads

Anton van Straaten anton at appsolutions.com
Thu Oct 2 16:32:22 EDT 2008

Andrew Coppin wrote:
> I thought ErrorT was a class name...?

No, it's the name of the error monad transformer type.  "Error" is just 
an ordinary monad, it's ErrorT that's the transformer.  So it sounds 
like the answer to your question below:

 > > You could try using an exception monad transformer here
 > I thought I already was?

...is no, you weren't.  You need to construct your monad stack using 
ErrorT, not Error.


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