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Re: The fundamental concept of continuations


From: gnuist006
Subject: Re: The fundamental concept of continuations
Date: Tue, 09 Oct 2007 06:33:24 -0000
User-agent: G2/1.0

On Oct 8, 11:07 pm, Bakul Shah <address@hidden> wrote:
> address@hidden wrote:
>
>  > Again I am depressed to encounter a fundamentally new concept that I
>  > was all along unheard of.
>
> The concept is 37 years old.  Wadsworth in his "Continuation
> Revisited" paper says he & Strachey were struggling with
> extending the technique of denotational semantics to describe
> jumps and not finding a satisfactory answer.  Then, in his
> words:
>
>    in October 1970 Strachey showed me a paper "Proving
>    algorithms by tail functions" by Mazurkiewicz [2] which he
>    had obtained from an IFIP WG2.2 meeting. Just the phrase
>    "tail functions" in the title was enough -- given the
>    experience of our earlier struggles -- for the ideas to
>    click into place! The (meaning of the) "rest of the program"
>    was needed as an argument to the semantic functions -- just
>    so those constructs that did not use it, like jumps, could
>    throw it anyway. The term "continuation" was coined as
>    capturing the essence of this extra argument (though I
>    often wished to have a shorter word!) and the rest, as they
>    say, is history.
>
>  > Its not even in paul graham's book where i
>  > learnt part of Lisp. Its in Marc Feeley's video.
>  >
>  > Can anyone explain:
>  >
>  > (1) its origin
>  > (2) its syntax and semantics in emacs lisp, common lisp, scheme
>  > (3) Is it present in python and java ?
>  > (4) Its implementation in assembly. for example in the manner that
>  > pointer fundamentally arises from indirect addressing and nothing new.
>  > So how do you juggle PC to do it.
>  > (5) how does it compare to and superior to a function or subroutine
>  > call. how does it differ.
>  >
>  > Thanks a lot.
>  >
>  > (6) any good readable references that explain it lucidly ?
>
> You might like this one:
>
> http://www.intertwingly.net/blog/2005/04/13/Continuations-for-Curmudg...

thanks for the link but can you plz upload the paper so we can also
get it.



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