[racket-dev] racket/date, SRFI-19, date construction

I don't know how important this is, but ideally serialized old SRFI-19 
dates should now deserialize as date*. I think that you can just restore 
the definition of deserialize-info:tm:date-v0 and change the second 
function (the cyclic value builder) to raise an error:

(define deserialize-info:tm:date-v0
   (make-deserialize-info
    srfi:make-date
    (lambda ()
      (error 'deserialize-info:tm:date-v0 "cycles not allowed"))))

and also restore the provide.

Ryan


On 01/11/2013 09:13 PM, Asumu Takikawa wrote:
> On 2013-01-11 15:39:08 -0600, Robby Findler wrote:
>>     I think it would be great if you were to find backwards-compatible
>>     ways to bring these two a little bit closer. Making them use the
>>     same internal date struct, for example, would be a great thing.
>
> I wrote a patch to make both of these use the same structure, attached
> to the e-mail. It seems to pass all of the srfi-19 and date tests (with
> some tests changed where appropriate). Does it look alright?
>
> It turns out there was one (sort of) good reason for SRFI-19 to define
> its own struct type: it used mutation for several functions. Racket's
> date/date* are immutable. I just changed these to use functional update.
>
> Another thing: when a string is converted to a date, it's possible that
> the format string only has time-of-day but no date specification.
> Previously, this produced a srfi/19 date with '#t's but I've now
> defaulted it to the start day of the Unix epoch (arbitrarily).
>
> Cheers,
> Asumu
>
>
>
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