Delimited Continuations and version control: an update

Posted on June 10, 2010, in continuations, darcs, imported

Last time I presented the idea that version control and delimited continuations are related.  I left off with a question how how to make Darcs fit this model.  I think I understand now what I was missing.

I forgot to think about Darcs operations in terms of the intermediate operations that get performed.  In Darcs, everything is based on commuting patches, even merging.  Therefore, to see how Darcs fits into this model it’s important to think about commuting patches in terms of delimited continuations.

Specifically, I now believe that commuting two patches introduces marks that can be shifted to later.

I have several ideas for the next steps of this.  One is to start modeling toy versions of svn and darcs in Haskell via delimited continuations.  After that, I would like to figure out the correspondence between the delimited continuations that I’ve identified and their data structure reification as zippers.  I hope to have more about that later.

Judging by a paper written by Oleg, there should be a natural way to convert the delimited continuation representation into a zipper.  Investigating this model might shed light on the Darcs patch model, or even lead to a more concise formalism.

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