HeuristicLab-Trac-Bot
commented
16 years ago 2008-03-31 00:52:10: @gkronber commented
I take the chance to describe some of my views in this ticket. I believe there are strong symmetries in the current evaluation model of HL and the evaluation model of Scheme. So the ideas I pursued the last few days are mainly about adapting the way name-binding is handled in Scheme for HL. This is in line with the idea of what we called 'Call'-objects in our previous discussion leading to ticket #57. The main concept being to move the functionality of scopes into two separate entities. My view is that scopes mix two separate concepts:
- Grouping simple values to an collection of values (which are moved and destroyed together)
a. Binding of names to values a. Binding of formal and actual names (over multiple steps)
The rough idea is to move bindings to 'environments' or 'frames' which are created by the engine for each application of an operator to a scope. The engine stores the mapping of actual to formal names for the current operator in the environment. Environments can be hierarchically linked (for instance when using
CombinedOperators). In the new model the scopes would only store variables in a structured and easily navigable data-structure same as now. Bindings in environments point to the data in the scope-tree. We could probably implement this almost in the same way as it is implemented in the scopes now.However the environment-model is probably bad in our situation. We have to remember that the scope-tree was designed especially in this way to make parallelization easy. The scheme environment-model is definitely not adequate for this and would have to be stripped down severely to prevent problems. There are also other minor issues that I won't discuss in this ticket. It should suffice to say that it gets messy quickly.
Anyway my conclusion for now is that while we might copy some smaller ideas from scheme it's probably not possible fully adapt the evaluation model of HL to it. Further discussions are needed.
Issue migrated from trac ticket # 95
milestone: HeuristicLab 3.3.0 | component: Core | priority: highest | resolution: done
2008-03-30 23:54:55: @s-wagner created the issue