Luke Palmer <[EMAIL PROTECTED]> writes: > Piers Cawley writes: >> I'd submit that, in the vast majority of cases you're not going to be >> dealing with full continuations, and on the occasions when you are the >> programmer using them will be aware of the cost and will be willing to >> pay it. > > Yeah probably. Except the problem isn't the cost. The problem is the > semantics. If you copy the registers, then when you invoke the > continuation, their *values* restore to what they were when you made the > continuation. These are not proper semantics, and would result in > subtle, incorrect infinite loops.
PMCs don't relocate, so the values you're restoring are simply the addresses of said PMCs. The Numeric registers are value registers anyway so no problem there (since there's no way of making a pointer to the contents of such a register AFAICT). I'm not sure about string registers. And anyway, copying is how it used to work, and work it did, albeit slowly.
