Hi all, My issue is generic Haskell use, but I should provide the specific background. I have some Snap code: eres <- eitherWithDB $ DB.findOne (DB.select [] "someCollection") let maybeVal = either (error "Mongoed") (maybe Nothing fromBson) eres and this works so that "maybeVal" will be of type Maybe MyType. "eres" is either a MongoDB Failure, or a Maybe Document (I find one document, or not). I'd like to convert this Maybe Document to a Maybe MyType without unpacking and repacking the Maybe. Is this possible? The fromBson function, that converts from a Document to an end user type, confuses me due to it's type: fromBson :: Monadhttp://hackage.haskell.org/packages/archive/base/4.5.0.0/doc/html/Control-Mo... m => Documenthttp://hackage.haskell.org/packages/archive/bson/0.1.7/doc/html/Data-Bson.ht... -> m a Thanks, Si