I should have called them "blueberries" instead of the more provocative
"virtual times." I was trying to go from an abstract mathematical
definition to a formalization in Clojure. Eventually, virtual times will be
part of a discrete-even simulation platform, but it's too early to say much
about that now. I'm just setting up the pylons at present.
Clojure number? excluding NaN will do for now: they have the required
semantics at the limits and they're comparable amongst Double, Integer,
Fraction, etc. Later, I may need a density axiom ("between any two finite
blueberries there is another blueberry") and that's not true for Doubles.
At that point I will definitely look back at your excellent answer and
consider s/fdef's.
On Monday, April 10, 2017 at 10:15:19 PM UTC-7, Didier wrote:
>
> Here it is adapted to use a deftype:
> https://gist.github.com/didibus/2ccd608ed9d226039f944b02a10f9ad5
>
> I gather from your solution that "orchestra" is not needed to spec :ret
>> types?
>>
>
> It is not. The return spec will be used during st/check. If you want the
> return spec to be validated outside of st/check though, than you need
> Orchestra.
>
> I shall have to read up on deftype versus defrecord.
>>
>
> I recommend the clojure.org explanation:
> https://clojure.org/reference/datatypes#_deftype_and_defrecord
> In a nutshell, deftype is a blank Java class, defrecord is an extended
> PersistentHashMap.
>
> I am not sure why you need a VirtualTime, and what it will be doing, so I
> can't really comment on which solution is best. As James said, it appears
> you might be creating something that behaves the same way Double does?
> Double already has positive and negative infinity and NaN:
>
> (/ 0.0 0.0) ; NaN
> (* 99e9999 99e9999) ; Infinity
> (* 99e9999 -99e9999) ; -Infinity
> (< Double/NEGATIVE_INFINITY Double/POSITIVE_INFINITY) ; true
> (= Double/NEGATIVE_INFINITY Double/POSITIVE_INFINITY) ; false
>
> I'd suggest, if you need Double, use Double. If you need something close
> to Double, and you can build on top of it, simpler to go with the style of
> my first gist. If you can't build on top of double, deftype is probably
> what you want.
>
> On Monday, 10 April 2017 21:41:35 UTC-7, Brian Beckman wrote:
>>
>> Wow... that's a comprehensive solution, Didier :) Bravo! It's a good
>> lesson for s/fdef, which I haven't yet studied. I gather from your solution
>> that "orchestra" is not needed to spec :ret types?
>>
>> As to semantics, on the one hand, I can spec ::virtual-time as a light
>> overlay over Double and risk conflation of ordinary operators like < <= =
>> etc. On the other hand, I have several options for full protection. I shall
>> have to read up on deftype versus defrecord.
>>
>
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