[racket] serialization of math/array

 So, there is currently no way make math/array serializable at all -- even when it would be ok to get an inefficient wrapped array as a result from deserialize? As far as understand, what hinders me from writing a simple typed wrapper for serialize/deserialize is that a typed struct does not support the #:property prop:serializable (simply ignored) at all and hence serialize complains about a non serializable value. Is this correct and would it be possible to add this property options with little effort?

Berthold


On 24.07.2014, at 14:52, Sam Tobin-Hochstadt <samth at cs.indiana.edu> wrote:

> On Thu, Jul 24, 2014 at 7:21 AM, Berthold Bäuml <berthold.baeuml at dlr.de> wrote:
>>> De-serializing an array of numbers and then passing it to typed code
>>> would produce a wrapper, not a first-order check, and so would be very
>>> expensive.
>> 
>> Even when first-order checks would be possible the cost of such a check would be significant in our application. We wan to use serialization/deserialization to send data between programs -- when running on the same computer the I/O cost (local sockets) would be almost negligible.
>> 
>> Would it be possible to have a typed serialization in the near future?
> 
> I think the Racket `serialize` API is likely to be higher-cost than
> that, even without considering Typed Racket.
> 
>>> What you want is something that can tell that the untyped reference is
>>> dead after value is passed to typed code, so that a first-order check
>>> can be used. This would require something new from Racket in the form
>>> of a revocable reference.
>> 
>> Does this also hold for immutable arrays? In this case a first-order check should suffice in principle.
> 
> Yes, for immutable arrays represented as flat data (not functions) the
> checks would not require wrappers.
> 
> Sam
> 
>> Berthold
>>> 
>> 
>>> 
>>> On Wed, Jul 23, 2014 at 11:52 AM, Matthias Felleisen
>>> <matthias at ccs.neu.edu> wrote:
>>>> 
>>>> Let's assume we serialize arrays of numbers, which is what I assume the background to the question is. In that case, the answer isn't all that obvious to me.
>>>> 
>>>> 
>>>> 
>>>> 
>>>> On Jul 23, 2014, at 11:47 AM, Sam Tobin-Hochstadt <samth at cs.indiana.edu> wrote:
>>>> 
>>>>> That really depends what the contracts are, and if they're first-order.
>>>>> 
>>>>> Sam
>>>>> 
>>>>> On Wed, Jul 23, 2014 at 11:45 AM, Matthias Felleisen
>>>>> <matthias at ccs.neu.edu> wrote:
>>>>>> 
>>>>>> Will these costs dominate the cost of I/O here?
>>>>>> 
>>>>>> 
>>>>>> On Jul 23, 2014, at 11:37 AM, Sam Tobin-Hochstadt <samth at cs.indiana.edu> wrote:
>>>>>> 
>>>>>>> Unfortunately, I think that strategy would incur substantial overhead
>>>>>>> for things like serialization of large arrays.
>>>>>>> 
>>>>>>> Sam
>>>>>>> 
>>>>>>> On Wed, Jul 23, 2014 at 11:28 AM, Matthias Felleisen
>>>>>>> <matthias at ccs.neu.edu> wrote:
>>>>>>>> 
>>>>>>>> On Jul 23, 2014, at 11:10 AM, Neil Toronto <neil.toronto at gmail.com> wrote:
>>>>>>>> 
>>>>>>>>> On 07/16/2014 10:25 AM, Berthold Bäuml wrote:
>>>>>>>>>> Hi,
>>>>>>>>>> 
>>>>>>>>>> will there be serialization support for math/array and math/matrix in the near future? As far as I understand in principle it should be possible at leas in  a straight forward way as there are  already the routines array->list and list->array.
>>>>>>>>> 
>>>>>>>>> Sorry it's taken so long to reply. Part of the problem is that `racket/serialize` isn't typed:
>>>>>>>>> 
>>>>>>>>> #lang typed/racket
>>>>>>>>> 
>>>>>>>>>> (require racket/serialize)
>>>>>>>>>> serialize
>>>>>>>>> Type Checker: missing type for identifier;
>>>>>>>>> consider using `require/typed' to import it
>>>>>>>>> identifier: serialize
>>>>>>>>> from module: racket/serialize in: serialize
>>>>>>>>> 
>>>>>>>>> 
>>>>>>>>> This and the fact that the array struct types are declared in Typed Racket makes adding serialization tricky at best. Also, it would only work in untyped Racket.
>>>>>>>>> 
>>>>>>>>> Generally, deserializing is hard to make type-safe, and nobody has taken it up yet for Typed Racket. Occurrence typing should help, but would require `deserialize` to take a predicate argument (like the second argument to `list*->array`), which it currently doesn't do.
>>>>>>>> 
>>>>>>>> 
>>>>>>>> Lucky us. I often leave the I/O parts of my programs untyped (I write either highly imprecise unchecked signatures or I don't provide types).
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>>>>>> 
>>>> 
>>> 
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>> 
>> --
>> -----------------------------------------------------------------------
>> Berthold Bäuml -- Head of Autonomous Learning Robots Lab
>> DLR, Robotics and Mechatronics Center (RMC)
>> Münchner Str. 20, D-82234 Wessling
>> Phone +49 8153 282489
>> http://www.robotic.de/Berthold.Baeuml
>> 
>> 
>> 
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-- 
-----------------------------------------------------------------------
Berthold Bäuml -- Head of Autonomous Learning Robots Lab
DLR, Robotics and Mechatronics Center (RMC)
Münchner Str. 20, D-82234 Wessling
Phone +49 8153 282489
http://www.robotic.de/Berthold.Baeuml