At some point in the past, someone wrote:
Actually, I've been wondering about this. If my understanding is correct, Haskell lists are basicly singly-linked lists of cons cells (is that correct?) A simple (I think) thing to do would be to make the lists doubly-linked and circular. That would let us do nice things like have O(1) primops for reverse, tail, (++) and other things that access lists at the end. However, I'm still pretty new to FP in general, so I don't know if there are any theoretical reasons why something like this couldn't work.
On Fri, Oct 08, 2004 at 02:42:28PM +0100, Keith Wansbrough wrote:
x = [3,5,7] primes = 2:x odds = 1:x You can't do sharing like this if your lists are doubly-linked; lots of cool algorithms depend on this sharing.
That constraint makes various other things painful. I suppose there is no one-size-fits-all solution. -- wli