Alberto G. Corona wrote:
* "Certainly a worthy research goal, but probably not what you had in mind :)"
*Not at all, My interest on that was on to improve RefSerialize. Although the Clean people has done a superb job on optimization. By the way, I'm not sure if uniqueness is the cause of his performance. I tested Haskell code generated using Maybe with and without monad instance and the monad does not impose any overhead at all.
Oh, I wasn't saying that monads impose any overhead. Rather, the Clean folks aren't fans of monads and so they use uniqueness typing in order to provide the same kind of solution to IO while retaining functional purity. GHC's implementation of IO is actually very similar under the hood to what Clean does, though that's not necessarily true of other monads. Even though they seem to intersect at IO, the ideas of monads and linear logics are orthogonal. The big optimization trick with linear logic is, since you know when some object is uniquely referenced, you know when it's safe to destructively update it in situ. For example, you can reverse a spine-unique list in linear time with zero space (modulo registers) by just inverting the spine pointers as you traverse it. Since it's uniquely referenced, noone else will notice so referential transparency is preserved. Doing it this way saves on allocation costs and on garbage collection. There are certainly other ways to use the information that some object is held only by a single reference, but Clean's optimizations are the first that leap to my mind. -- Live well, ~wren