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A comment on I'm Sick of This. Parent comment

Re:I'm Sick of This by jrockway on Wednesday April 08, 2009 @11:35AM (#552839)
I don't think this is quite what Worlds are. Worlds would not allow you to have a data structure that is used by both Rails and Classifier.

FWIW, ContextL is closer to the solution:

http://common-lisp.net/project/closer/contextl.html

But it's still better to just add a standard "array that does 'sum'" to the language, or for Rails and Classifier to cooperate.

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Re:I'm Sick of This by stcredzero on Wednesday April 08, 2009 @12:39PM (#552953)
Cooperation is dandy if n = 2, but for n > 2, this can get cumbersome. Unfortunately method names like 'sum' are very attractive.

A language/library designer shouldn't have to think of "all of the short or otherwise possibly overloaded nouns and verbs people might like to use, ever." Being able to say you are going to do a 'sum' which means X in this particular context is very powerful.

This notion should also be unified with version control. (As in OS X, where a process only sees the versions of libraries that it is supposed to run against.)

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Re:I'm Sick of This by jrockway on Wednesday April 08, 2009 @01:31PM (#553047)
A language/library designer shouldn't have to think of "all of the short or otherwise possibly overloaded nouns and verbs people might like to use, ever." Being able to say you are going to do a 'sum' which means X in this particular context is very powerful.

In this specific case, what's needed is more abstraction. Consider the approach Haskell takes:

http://www.haskell.org/ghc/docs/latest/html/libraries/base/D...

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Re:I'm Sick of This by andreyf on Wednesday April 08, 2009 @12:33PM (#552942)
Worlds would not allow you to have a data structure that is used by both Rails and Classifier.

I might be misunderstanding it... but why not?

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Re:I'm Sick of This by arebop on Wednesday April 08, 2009 @08:53PM (#553706)
It seems to me that worlds permit sharing immutable data structures, and that Warth & Kay's operations on worlds do not permit sharing mutations done in parallel worlds.

The Worlds paper you cited [http://www.vpri.org/pdf/rn2008001_worlds.pdf] cites the COP overview paper [http://p-cos.net/documents/contextl-overview.pdf] mentioned near the top of the link jrockway gave. Warth & Kay say "Similarly, in order to support context-oriented programming (COP) [8], we may want to add a third key to our lookup table that identifies a context." So that gives me some confidence in my interpretation.

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