Give update.formula() an option not to simplify or reorder the result -- request for comments

With a bit of meta programming that manipulates expressions, I don?t think this would be difficult to implement in a package. Well, as difficult as it is to implement a CAS, but not harder. I wrote some code for symbolic differentiation ? I don?t remember where I put it ? and that was easy. But that is because differentiation is just a handful of rules and then the chain rule. I don?t have the skills for handling more complex symbolic manipulation, but anyone who could add it to the language could also easily add it as a package, I think.

Whether in a standard package or not, I have no preference whatsoever.

Cheers
Thomas

Martin Maechler has asked me to send this to R-devel for discussion
after I submitted it as an enhancement request (
https://bugs.r-project.org/bugzilla/show_bug.cgi?id=17563).

I think R needs to provide more support for CAS-style symbolic computation.
That is, support by either the R language itself or the standard packages,
or both.
(And certainly not by interfacing with another interpreted language).

Obviously, I don't speak for R Core.
However, this is how I would like to see R move in the future.
...improved symbolic and symbolic-numeric computation...

I think any changes to formula objects or their methods, should be
congruent with these symbolic improvements.


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