[racket] serialization of math/array

OK. I am beginning to wonder whether we're missing something in the contract world. 






On Jul 23, 2014, at 12:00 PM, Sam Tobin-Hochstadt <samth at cs.indiana.edu> 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.
> 
> 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.
> 
> Sam
> 
> 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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>>>> 
>>