2009/1/15 Andrew Coppin
OK, well then my next question would be "in what say is defining configuration files as a monoid superior to, uh, not defining them as a monoid?" What does it allow you to do that you couldn't otherwise? I'm not seeing any obvious advantage, but you presumably did this for a reason...
I can't speak from the perspective of the Cabal developers, but combining configurations with partial information using a monoid operation is generally a good way to structure things. Basically, this would be analogous to the way that the First monoid (or the Last monoid) works, but across a number of fields. You have an empty or default configuration which specifies nothing that serves as the identity, and then a way of layering choices together, which is the monoid operation. - Cale