[Haskell-cafe] ErrorT and catchError question

Brandon S. Allbery KF8NH allbery at ece.cmu.edu
Tue Jan 15 22:34:42 EST 2008

On Jan 15, 2008, at 22:05 , Adam Smyczek wrote:

> Ups, resend, first response did not make into the list.
> On Jan 14, 2008, at 9:33 PM, Brandon S. Allbery KF8NH wrote:
>> On Jan 15, 2008, at 0:28 , Adam Smyczek wrote:
>>> It's probably a trivial question, but I cannot figure out
>>> how to implement the catchError function in:
>>> instance MonadError String Shell where
>>> 	throwError      = error . ("Shell failed: "++)
>>> 	catchError l h = ???
>> Take a look at Control.Exception.catch for starters.
> No, did not help and
> going over the source code of Control.Monad.Error did not
> help as well. Does someone have other tips for me?

Perhaps you could explain what you're looking for?  Your typeclass  
doesn't tell us anything about the semantics.

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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