[Caml-list] lazy and marshal

[Caml-list] lazy and marshal

[sicard]

Hello
I don't understand the following error :
Marshalling a lazy value don't work when the value has not been computed.


# let a = lazy 0;;
val a : int lazy_t = <lazy>
# Marshal.to_string a [ Marshal.Closures ] ;;
Exception: Invalid_argument "output_value: abstract value".

# Lazy.force a;;
- : int = 0
# Marshal.to_string a [ Marshal.Closures ] ;;
- : string =
"\132\149??\000\000\000\001\000\000\000\000\000\000\000\000\000\000\000\000@"
#

Thanks

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Re: [Caml-list] lazy and marshal

[Kip Macy]

Marshal stores values or data structures, a lazy value by definition 
is one whose evaluation has been deferred. In order for the marshalling
of lazy values to work, the thunk (or however deferred evaluation is 
handled in ocaml) and all the environment that it depends on would have
to be marshalled.

On Tue, 17 Jun 2003 sicard@poleia.lip6.fr wrote:

> Hello
> I don't understand the following error :
> Marshalling a lazy value don't work when the value has not been computed.
> 
> 
> # let a = lazy 0;;
> val a : int lazy_t = <lazy>
> # Marshal.to_string a [ Marshal.Closures ] ;;
> Exception: Invalid_argument "output_value: abstract value".
> 
> # Lazy.force a;;
> - : int = 0
> # Marshal.to_string a [ Marshal.Closures ] ;;
> - : string =
> "\132\149??\000\000\000\001\000\000\000\000\000\000\000\000\000\000\000\000@"
> #
> 
> Thanks
> 
> -------------------
> To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr
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Re: [Caml-list] lazy and marshal

[Damien Doligez]

On Tuesday, June 17, 2003, at 05:21 PM, sicard@poleia.lip6.fr wrote:

> Hello
> I don't understand the following error :
> Marshalling a lazy value don't work when the value has not been  
> computed.
>
>
> # let a = lazy 0;;
> val a : int lazy_t = <lazy>
> # Marshal.to_string a [ Marshal.Closures ] ;;
> Exception: Invalid_argument "output_value: abstract value".
>
> # Lazy.force a;;
> - : int = 0
> # Marshal.to_string a [ Marshal.Closures ] ;;
> - : string =
> "\132\149??\000\000\000\001\000\000\000\000\000\000\000\000\000\000\000 
> \000@"
> #


# Marshal.to_string (fun x -> x) [ Marshal.Closures ];;

You cannot marshall the functional values that are compiled
by the toplevel.  This is a limitation of the toplevel, not
lazy values.

-- Damien

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Re: [Caml-list] lazy and marshal

[Pierre Weis]

> You cannot marshall the functional values that are compiled
> by the toplevel.  This is a limitation of the toplevel, not
> lazy values.
> 
> -- Damien

Could you elaborate a bit on this ?

What is specific to the functional values compiled by the toplevel ?

Pierre Weis

INRIA, Projet Cristal, Pierre.Weis@inria.fr, http://pauillac.inria.fr/~weis/


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Re: [Caml-list] lazy and marshal

[Damien Doligez]

On Thursday, June 19, 2003, at 11:46 AM, Pierre Weis wrote:

>> You cannot marshall the functional values that are compiled
>> by the toplevel.  This is a limitation of the toplevel, not
>> lazy values.
>>
>> -- Damien
>
> Could you elaborate a bit on this ?
>
> What is specific to the functional values compiled by the toplevel ?

Their byte-code is allocated dynamically and does not lie between
code_area_start and code_area_end.

-- Damien

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