[plt-scheme] likely 3.99.0.22 -> 3.99.0.23 incompatibility: hash tables

Matthew Flatt wrote:

> While we're cleaning up the language in v4, we'd like to do something
> about the API for using hash tables:

I appreciate and support the idea of simplifying the syntax, but the use 
of both "table" and "hash-table" confuses me. I suppose it is related to 
this:

> * Add some property for creating new kinds of tables. The property
>    value supplies an implementation for `table-ref', etc.

Can you sketch an example of how this would work?

I would like to be able to use this datatype in a more functional 
manner. That's true for vectors as well, though there I suspect that 
what I need is a "write-once" version of make-vector where the function 
mapping integers to values can reference other defined values -- this is 
what is needed for many table-driven algorithms (e.g. dynamic 
programming). But I guess I can write a macro for this, rather than 
asking for it to be a primitive. --PR