Re: [Toss-devel] Specification of Hierarchical Terms

[Lukasz K. <luk...@gm...>]

> The move to left-linear rules is nice in that after introducing
> sharing (according to the proposal), the semantics of non-linear rules
> change: sharing in pattern requires sharing in matched (sub)term.

That was the idea - to help with sharing in the future. I also thought
about making the rules right-linear and adding a "where" clause, e.g.
instead of "f(x, x)" you would write "f(x, y) where y = x". This could
allow to distinguish copying from sharing - we will probably need both,
and we could have "f(x, y) where y = copy(x)" and f(x, y) where y == x",
or something like this, with the second one meaning a shared term.
But let's concentrate on glb/isa now, I guess this is enough to do ;).

Lukasz