[plt-scheme] Native code generation and immutable pairs

On 2/11/06, Robby Findler <robby at cs.uchicago.edu> wrote:
> I don't know if anyone answered your question, but yes. We are
> considering that and have been for a long time. Partly because it
> improves analyses like you suggest, but more because it makes it easier
> to reason about programs using immutable conses (and contract systems
> work better when structures are immutable). In particular, you can hand
> out the same list multiple times from a library without having to worry
> about copying it to be safe/correct.

What were your thoughts about the flip side argument: that it's
valuable to treat mutable pairs as a subtype of pairs?  SRFI-1 thought
it valuable to provide an extensive set of "linear" operators; and the
body of code distributed with MzScheme seems to use set-car! and
set-cdr! quite a bit.

In other words, how do you folks feel about what you'd be giving up?