So, what the heck is a continuation anyway?

[Dan Sugalski <address@hidden>]

Okay, so here's where I get to air my ignorance in public.

I've been working on the design of the Parrot VM and it's pretty well 
nailed down. All the stuff I need done (good method dispatch, attributes, 
coroutines, continuations, threads, I/O, GC, language-independent calling 
conventions, higher-order functions) is at least sketched out. Devil's in 
the details, of course, but at least there are spots for the details to go. 
Someone's even started in on a JIT for the thing. (x86 only for the moment, 
but...)

The final issue is continuations.

I'm not sure I need to support 'em. Perl, python, and ruby don't use them 
to the best of my knowledge, and I've been told that Scheme doesn't require 
them, but I'd like to build support in from the beginning, as I expect 
it'll be rather a pain to add it in later. Unfortunately I don't understand 
the things at all--I can't wrap my brain around any of the explanations 
I've seen.

Could someone give me an explanation of them? (Preferably in words of three 
syllables or less, geared towards an inveterate assembly language 
programmer? :)

					Dan

--------------------------------------"it's like this"-------------------
Dan Sugalski                          even samurai
dan@sidhe.org                         have teddy bears and even
                                      teddy bears get drunk