Bill Page wrote:
You are right that I did not state this properly. Of course we can
evaluate expressions (including functions) that return domains
and categories. What I was trying to say is that domains in Spad
and Aldor are immutable during run-time. Once constructed their
"value" is constant and can not be changed. For example we
can not insert or remove anything in the list of exports or even
replace one exported function with another during the execution
of the program. This is possible in Python.
Note: I am not talking about the post facto library extension feature
in Aldor. 'extend' is a compile-time operation.
I want comment about Alder, but in current Axiom runtime domains are
mutable. In fact I think that ability to redefine domain at runtime
was an important design goal (otherwise a sigificant part of Axiom
runtime activities would be useless).