[Axiom-developer] Embedding Axiom (Hickey and fold/unfold) and Reifying time

[Tim Daly]

Martin Baker wrote:
> On Friday 20 November 2009 23:17:25 Tim Daly wrote:
>   
> > There is an excellent talk by Rich Hickey about modelling time, 
> > identity, values,
> > perception, state, memory, etc.
> >     
>
> Tim,
>
> While I was watching this talk I was wondering about the difference between 
> the mainstream computing issues verses mathematical computing issues.
>
> I get the impression that the mainstream issue, from this talk, is about how 
> to run multiple algorithms in parallel?
>
> If we are trying to solve a set of equations, is there a natural parallelism ? 
> For the reasons discussed in the talk, should a rule based method be preferred 
> wherever possible and explicit coding of algorithms be discouraged?
>
> Martin Baker
>
>   
Reifying time...

All of that being said, I think that there is a lot to learn from 
Hickey. There is certainly
a lot to be gained by writing in a functional programming style (which 
Axiom is not
using internally now).

I found his idea of reifying time interesting. Time, according to 
Hickey, is not a flow
but an ordering on a set so you cannot measure A-B but you can decide A<B.
I would use this "reify time" idea and combine it with locking 
primitives. The lock
variable could be a timestamp. That would be unique and it would enable 
me to
know if A was changed before B. Access to the system clock could be made
unique so that no two timestamps can be equal unless they were performed by
the same process.

I really love his immutable data structures work. I am sorely tempted to 
rewrite some
of the internals to use these.