On Tue, Jan 30, 2007 at 10:22:58AM +0000, Duncan Coutts wrote:
I was about to say that for the more complicated binary serialisation formats (eg GHC's .hi format) people need monads with state, like string pools etc, but actually now that I think about it, that can be done with a monoid too.
Ross, you need to make a monoid transformer library (at least reader and state) and campaign for ++ to be redefined as mappend, then everyone will want to use it since it'll be so neat and convenient! :-)
Can anyone see a real serialisation use case that needs a monad for the serialisation side? I'd thought I had an example, but I was wrong.
If you really want a monad, you can put the monoid into the writer monad - and that's exactly what is done in Data.Binary! However, for someone who prefers the monadic interface, wrapping in the writer monad every time and additional boilerplate code (tell) can be a nuisance. Best regards Tomasz