Taylor Campbell wrote:
Scott and I seem to disagree on this. Here's a log of our debate about it on IRC tonight: (I'm Riastradh; Scott is FoxFire)<Riastradh> Dictionaries' *-GET should take an optional failure continuation, not default value....
I would very much like to see *any* kind of function (promise, continuation, procedure) there rather than simply a default value.
The use of exceptions is a popular style. Also there are more exotic applications such as using a secondary retrieval on a cache failure.
I believe a procedure taking the arguments supplied to the original call (whether fold, get, update), although a bit ugly, would easily support any application need without a performance penalty when simply providing a fixed default value.
Jim --"I love deadlines. I love the whooshing sound they make as they fly by." -- Douglas Adams