Also, could you go backwards and then continue from the final state in
order to avoid forking the history?


On Tue, Nov 27, 2012 at 2:36 PM, Mark Hahn <[email protected]> wrote:

> >  When you go backward what has already happened won't change.
>
> Awesome.  So it is the answer to my dream of going backwards to see what
> caused some state change.
>
> Could this be used in a real app?  It seems the expansion of code would
> slow things down too much to observe a real app's behavior.  Also the
> memory usage of all the data-structures would be excessive in long running
> apps.  Maybe there could be a trimmed down version that only keeps a finite
> amount of history so the app could run forever?
>
> I'm not knocking it.  It is useful in a zillion instances I can think of,
> not just teaching.
>
>
>
> On Tue, Nov 27, 2012 at 2:17 PM, Cryptic Swarm <[email protected]>wrote:
>
>> 1) Can someone tell me what a sha (sp?) dictionary is?
>>
>> Sha -> Hash.  In the video those were Sha1 hashes.
>> Dictionary -> JavaScript Object
>>
>> Example:
>> { '3b9e33965edbaf4094947aca1b8d59eacfd2ef47': { usefulInfo:123 },
>>   '98cbccef9dd0f6f70a48baf03fdfb98fb0f70b4f': { moreInfo: 456 } }
>>
>>
>> 2) It seems this would mainly be useful as a teaching tool because I
>>> don't see how it could work with non-deterministic behavior such as io
>>> events.
>>
>>
>> Yes, mainly useful for teaching/learning purposes, but not really because
>> of io events.  Once something happens it, it happened.  The data-structures
>> are immutable.   When you go backward what has already happened won't
>> change.  However, when you go forward again you will potentially fork the
>> computation tree (if going forward has a different side effect than
>> previously).
>>
>> Example:
>> var x = Math.random()
>>
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>

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