On Sun, 2009-10-18 at 19:53 +0400, Alexey Khudyakov wrote:
Yes. We decided that having the Get monad as a lazy state monad just doesn't make sense. It makes this one use case work, but causes more problems generally. Certainly we need to be able to do lazy binary deserialisation too, but our feeling is that it should be more explicit and integrate better with error handling. Using a lazy state monad gives us neither.
This is valid point. I think I'll just use variant with explicit laziness.
Note also that if we changed runGetState to do any error handling that this would also break the lazy state monad properties that you were previously relying upon.
I'd appreciate addition of error handling very much. Currently I have to use ErrorT and do checks by hands. I have very simple parsers so it's possible. It's not possible to do such things in general.
Trading laziness for error handling is good thing I believe. At the moment it's hard to decode possibly malformed data.
It's possible to have both error handling and lazyness by extending the result to include the representation of the errors. Duncan