Pros and cons for software enforced variable types?

[Colin Smart]

Hello,

Pardon the cross post.

I am looking for pointers to papers, articles etc. which address the
issue of software enforced variable type definition.

I realize that some packages do use/enforce types while others merely
pay lip service to the concept, e.g. allowing the user to take the mean
of an ordered categorical variable.

Any pointers, thoughts etc. very welcome. I'll summarize the responses
later.

Thanks,

Colin