Re: tolog for TMQL

* Robert Barta
> 
> - tolog allows to quantify over literals, i.e allows to have
>  variables range unboundedly (TMQL@rho never does allow that)

No, this is not allowed.

str:length($A, 5)

is not legal.

>    - you cannot flatten a set of tolog predicate evaluations into a
>      stream of expressions, say, path expressions, to, say,
>      evaluate those in parallel. Sharding with tolog query
>      expressions should work, though.

So we agree that both can be run in parallel. However, you seem to claim that there is a way to run TMQL@rho in parallel, that isn't possible with tolog. I've no idea what this difference is, though.

>      Variables always mean _state_ information and I certainly do
>      not need to tell you that carrying around //state// impedes
>      concurrency.

There's just as much state in a path language. The difference is whether the values have names or not.

> I transformed a
> 
> for $p in // person
> where
>    is-author (author: $p, opus: $_)
> 
> into a chain of PEs which did not contain a single variable. The
> semantics appendix in TMQL@rho has a complete transformation defined.


What does it matter if there are variables or not? Surely what matters is how/whether you can compose/decompose query expressions, and not whether there are variables.

--Lars M.
http://www.garshol.priv.no/tmphoto/
http://www.garshol.priv.no/blog/