On Sun, Dec 13, 2009 at 02:11:28AM +0000, Glurk wrote:
What's got me a little puzzled at the moment is non mutable data. [...] How do people see this kind of situation ? Is it just the way of looking at it... ? Do I just accept that I toss out my old library object, and have a new one, which happens to be the same as the old one, except for the "new" book which is now borrowed ?
Do I really need to get over thinking of objects in the first place, even though it's what I see exist in the real world ?
Mutability perhaps more directly matches how we look at the world, in which objects have states that change over time. Purely functional programming doesn't allow mutating data in place, so we have the "evolution" of an object through time. We get multiple snapshots. I like to think of it as having 1 dimensional objects instead of having 0 dimensional objects, in direct analogy to thinking of objects in the world as being 4 dimensional: 3 spatial and 1 time dimension. Rich Hickey (the Clojure guy) gave a keynote talk about this kind of thing: http://www.infoq.com/presentations/Are-We-There-Yet-Rich-Hickey Here's an interview about the same thing: http://www.artima.com/articles/hickey_on_time.html I've only watched the keynote, which I found really interesting. Maybe these will better help you get a grasp on a "functional" way of thinking? Hope that helps, John