Re: [Haskell-cafe] Re: persist and retrieve of IO type?

Can you please explain this: ....the parameters baked into the thunk may be infinite....

daryoush On Sat, Apr 10, 2010 at 6:27 AM, Svein Ove Aas wrote:

On Sat, Apr 10, 2010 at 11:19 AM, Jon Fairbairn wrote:

...

It sounds more like he wants two functions something like

save:: FilePath -> [IO ()] -> IO () restore:: FilePath -> IO [IO ()]

to which the answer would be no.

It's an insoluble problem in general - the parameters baked into the thunk may be infinite, or at least too large to persist, and the functions may not be around if you try to load the persisted data into a different version of the executable - but it's an interesting problem to attempt solving.

Given that GHC 6.12 has added some of the base functionality required (i.e. dynamic linking), I was planning to take a bash at it (persisting functions in general, not just IO actions) in the summer.

I don't know if that would help you, though. It's certainly not a good idea in general, and at any rate there's a good chance I won't succeed.

(Of course, thunks aren't /actually/ infinite, in memory. Part of the project would be an attempt to persist the thunks, allowing lazy evaluation after reading them back in. Naturally this would only work with the exact same executable, but that's not necessarily a problem.)

-- Svein Ove Aas _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe