[Axiom-developer] Re: EXPR POLY INT

[William Sit]

root wrote:

>Martin,
>
> Historically EXPR was an attempt at creating a domain where the user
> did not need to be concerned about types. There was (and still is)
> great pressure from users of competing CA systems to be able to work
> and let the interpreter worry about types. EXPR was an attempt at
> responding to that.

I believe ANY is the domain to encompass all objects of arbitrary type and ANY
depends on manipulating Lisp values via SEX (I know that will get your
attention!) I think this is the work of Bob Sutor.

> The best path is probably to avoid EXPR. Is there some function in
> EXPR that you need that does not exist elsewhere?

EXPR is used for many constructions, for example, the algebraic closure of the
field of rational numbers, or the domain AlgebraicNumber in Axiom is represented
as EXPR INT. An understanding of EXPR is a must to do any computation with
algebraic numbers and that includes integration and differential equations. 

William