On 6/22/07, Carl Eastlund <cce at ccs.neu.edu> wrote:
>
> On 6/22/07, Onnie Winebarger <owinebar at gmail.com> wrote:
> > Is this the only way to achieve that goal, or just a convenient one?
> > It is an unfortunate decision, in any case. The Scheme that makes
> > impurity second-class is not the true Scheme.
>
> In this setup, it's easy to achieve a guarantee of purity (don't
> import set-c[ad]r!), and easy to achieve impurity (import them). It's
> a one-line difference. In previous Schemes, impurity is the default
> but achieving purity requires examining the whole program, and there
> was no builtin mechanism to guarantee it. I think the R6RS solution
> comes closer to making both kinds of programming first-class.
The legacy of Scheme's invention is not to make things easy for
implementors. It is to challenge implementors to make a useful feature or
programming style usable while embracing functional, imperative, and
declarative paradigms.
Lynn
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Received on Fri Jun 22 2007 - 14:31:30 UTC