Re: persistant state in guile-log

[Andrew Gaylard <a.gaylard@gmail.com>]

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Hi Stefan,

This is definitely something that's of interest to me.  Closures are one 
of the great strengths of scheme, and have been very useful to me in the 
past.

I'd love it for guile to have an "official" way to work with them, 
including your load/save semantics.  What's the format of the saved 
state? — is it human-readable or just readable by guile?

In addition it would be great for guile to be able to reason about the 
current state: e.g. walk the call stack and examine what's in it, or 
even change it.  (Perhaps this is already possible, I haven't checked.)

-- 
Andrew

On 27/01/2016 10:13, Stefan Israelsson Tampe wrote:
> Hi all,
>
> In guile 2.1 the position of code segements are fixed relative certain 
> vectors and this makes it
> possible to store indexes of code segements and as a possibility to 
> persist closures. I took advatage of this because state in guile-log 
> means that we must do exactly that. Persist not only datastructures 
> like struct lists and vectors vhashes etc, but also persist closures. 
> So now one can do cool things in guile-prolog like:
>
> prolog>  X=1,stall,Y=2.
> prolog> .setp 1
> prolog> .savep
> prolog> .quit
>
> stis> guile-prolog
> prolog> .loadp
> prolog>  .refp 1
> prolog> .cont
>
>   X=1
>   Y=2
>
> prolog>
> This is the interface:
> ---------------------------------------------------------------------
> (.setp        ) <key> associate current state to key
> (.refp        ) <key> instate state referenced by key to current state
> (.savep       )             save all referenced states to disk
> (.loadp       )             load new referenced states from disk
> (.cont         ) continue a stalled predicate from current state
>
> I can make this persistant code into a library anyone interested?
>
> Oh the security implications of this is horrible but I don't pretend 
> that guile-log is secure so
> I don't care. What's more demading is that it depends on groveling 
> into guile internal datastructures. Therefore I am reqesting an 
> official way of persisting closures. What's your take on that? Would you
> guy's want to supply such a mechansim or is it bad practice?
>
> regards
> Stefan


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