Re: [Haskell-cafe] Re: Can this be done?

On Thu, 2009-02-12 at 19:55 -0500, Chung-chieh Shan wrote:

wren ng thornton wrote in article <4993BBEE.9070603@freegeek.org> in gmane.comp.lang.haskell.cafe:

...

It's ugly, but one option is to just reify your continuations as an ADT, where there are constructors for each function and fields for each variable that needs closing over. Serializing that ADT should be simple (unless some of those functions are higher-order in which case you run into the same problem of how to serialize the function arguments). In GHC's STG machine this representation shouldn't have much overhead, though it does require the developer to do the compiler's job.

FWIW, this idea is called defunctionalization (due to Reynolds), and it works for higher-order functions as well (because you can defunctionalize those function arguments in the same way).

People in many fields put a lot of effort into turning their programs into state machines...

This paper by Ezra Cooper and Phil Wadler is an interesting recent development in the theory of defunctionalization and very relevant to this particular topic as well: http://homepages.inf.ed.ac.uk/wadler/topics/links.html#located-lambda