To use the hash, I have to convert it to a ByteString, and then I suddenly have lost all this safety. I don't really see how there is any real safety gained. That said, just exposing a direct method of getting to that ByteString without cereal (as Thomas proposed) would be an improvement. Aristid 2012/1/8 Vincent Hanquez :

On 01/08/2012 04:12 AM, Aristid Breitkreuz wrote:

...

Why? I don't actually need the hash object for anything, usually. All I need is the ByteString, and then I need to learn how to use the cereal package to get it...

The whole rationale i believe, is having meaningful types associated to your values so that the type checker can do its job. i.e. you don't start mixing a hash (in binary form) and a random piece of file.

My only problem with the Serialize instance, is that dependencies (cereal in this case) trickle through to the user of the API, which would be solved by Thomas' suggestion.

-- Vincent