Comments on: Demystifying Continuations in Ruby (because they shouldn’t be feared) http://gnuu.org/2009/03/21/demystifying-continuations-in-ruby/ my word against yours, fight. Thu, 29 Jul 2010 07:40:54 +0000 hourly 1 http://wordpress.org/?v=3.0 By: James McKinney http://gnuu.org/2009/03/21/demystifying-continuations-in-ruby/comment-page-1/#comment-153 James McKinney Tue, 24 Mar 2009 21:35:10 +0000 http://gnuu.org/2009/03/21/demystifying-continuations-in-ruby/#comment-153 i agree continuations aren't complicated, just some of the uses to which they are often put; I wasn't disagreeing. I'm just saying that (without having read the same blogs and articles about continuations that you have) I can only assume, being charitable to those authors, that the parts of the articles that were over-complicated were probably those that dealt with the uses of continuations. It's easy to explain code that uses one stack; it can get messy to explain code that saves and restores stacks regularly. i agree continuations aren’t complicated, just some of the uses to which they are often put; I wasn’t disagreeing.

I’m just saying that (without having read the same blogs and articles about continuations that you have) I can only assume, being charitable to those authors, that the parts of the articles that were over-complicated were probably those that dealt with the uses of continuations. It’s easy to explain code that uses one stack; it can get messy to explain code that saves and restores stacks regularly.

]]> By: Loren Segal http://gnuu.org/2009/03/21/demystifying-continuations-in-ruby/comment-page-1/#comment-152 Loren Segal Mon, 23 Mar 2009 19:37:04 +0000 http://gnuu.org/2009/03/21/demystifying-continuations-in-ruby/#comment-152 I think you're confusing the functionality of continuations with its potential uses. You may not use a continuation "as" a goto, but when you use a continuation all its doing is exactly what I described above. Continuations by themselves have no other functionality but to jump to a point in code with a saved stack frame. What you use them for, well, that's a different story altogether. The point being, using continuations to do tail recursion should be as simple as doing tail recursion with a goto statement. That certainly sounds simple enough to me. You can use "goto"s as if statements, case switches and more. Does that make the goto statement complicated? Not in the least. Similarly, using continuations as a component in more complex patterns shouldn't make its usage any more mystical; it's still just a "glorified goto". I think you’re confusing the functionality of continuations with its potential uses. You may not use a continuation “as” a goto, but when you use a continuation all its doing is exactly what I described above. Continuations by themselves have no other functionality but to jump to a point in code with a saved stack frame. What you use them for, well, that’s a different story altogether.

The point being, using continuations to do tail recursion should be as simple as doing tail recursion with a goto statement. That certainly sounds simple enough to me. You can use “goto”s as if statements, case switches and more. Does that make the goto statement complicated? Not in the least. Similarly, using continuations as a component in more complex patterns shouldn’t make its usage any more mystical; it’s still just a “glorified goto”.

]]> By: James McKinney http://gnuu.org/2009/03/21/demystifying-continuations-in-ruby/comment-page-1/#comment-148 James McKinney Sat, 21 Mar 2009 22:56:26 +0000 http://gnuu.org/2009/03/21/demystifying-continuations-in-ruby/#comment-148 Uhh, I think it's exactly that continuations can save and restore execution state that makes them interesting and possibly confusing to some. Sure, you can use a continuation as a goto, but that's not all you'd want to use one for. It's these other uses require a little more explanation (although I agree that most bloggers do a poor job of it and make it out to be harder than it is). Continuations allow you to do, for example, tail recursion and lazy evaluation, whose implementations someone, with only the understanding of continuations that you impart here, wouldn't be able to understand. Uhh, I think it’s exactly that continuations can save and restore execution state that makes them interesting and possibly confusing to some. Sure, you can use a continuation as a goto, but that’s not all you’d want to use one for. It’s these other uses require a little more explanation (although I agree that most bloggers do a poor job of it and make it out to be harder than it is). Continuations allow you to do, for example, tail recursion and lazy evaluation, whose implementations someone, with only the understanding of continuations that you impart here, wouldn’t be able to understand.

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