What Does "With Continuation" Mean? (2020)
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What Does "With Continuation" Mean? (2020)
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Re: What Does "With Continuation" Mean? (2020)
#2Here's Oleg's great explanation of continuations in terms most programmers already understand: https://blog.moertel.com/posts/2008-05-05-olegs-great-way-of...
Re: What Does "With Continuation" Mean? (2020)
#3I'm just happy to see Professor Harvey still participating in the forums. He taught me SICP in Scheme 27 years ago and it is still some of the most important computer science I ever learned.
Re: What Does "With Continuation" Mean? (2020)
#4I'm glad that this explanation involves a comparison with goto especially with a discussion of "goto considered harmful". But IMO excessively using continuations results in the same kind of spaghetti code as code that excessively uses goto. Delimited continuations, on the other hand, essentially places a restriction on where the continuation can return to. The analogy with using goto is that the target of the goto has to be within a well specified block of code. This restriction gets rid of the temptation by programmers to take shortcuts and write overly clever but unmaintainable code.
Re: What Does "With Continuation" Mean? (2020)
#5Required reference "Objects the poor man's Closures[continuations]" [1]. Well, the links actually say "Closures And Objects Are Equivalent", which is the point. But I'd offer a deeper point - continuations/closures are rightly considered one of the hardest things most programmers ever encounter while objects are things most programmers deal with daily. Sure, that means use continuations if you want to look like a bad ass but use objects if you want a project to succeed.
Re: What Does "With Continuation" Mean? (2020)
#6(2020)
Re: What Does "With Continuation" Mean? (2020)
#7Here's Oleg's great explanation of continuations in terms most programmers already understand: https://blog.moertel.com/posts/2008-05-05-olegs-great-way-of...
call/cc is undelimited.
Re: What Does "With Continuation" Mean? (2020)
#8I'm just happy to see Professor Harvey still participating in the forums. He taught me SICP in Scheme 27 years ago and it is still some of the most important computer science I ever learned.
Same! (CS 61A Fall Semester 1996) And I agree!
Re: What Does "With Continuation" Mean? (2020)
#9I took a Scheme programming class where we did tons of stuff with continuations. I got obsessed and wrote all kinds of weird code. I even started using continuation passing style in Python. It was a dark time. Looking back, none of that code makes any sense at all.
When I think back to my days of mucking around with call/cc my main emotion is relief that I’ve forgotten how it works. It’s a load off my mind
Re: What Does "With Continuation" Mean? (2020)
#10I took a Scheme programming class where we did tons of stuff with continuations. I got obsessed and wrote all kinds of weird code. I even started using continuation passing style in Python. It was a dark time. Looking back, none of that code makes any sense at all. When I think back to my days of mucking around with call/cc my main emotion is relief that I’ve forgotten how it works. It’s a load off my mind
In case first-class continuations scare anyone away from Scheme: you probably will never use it directly in practice, unless you're doing something very unusual that happens to really need it.
For example, say you have a really hairy AI search algorithm, capturing a continuation happens to make backtracking easier.
Or you're implementing another language or DSL in Scheme, and you use first-class continuations to implement some control structure semantics exactly how you want them to be.
I think the closest I've used, in writing maybe a hundred modules, is an escape procedure (like a premature `return` statement in many other languages, which you generally avoid in idiomatic Scheme).