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Re: Why would anyone want opacity?
Date: Tue, 30 Apr 1996 16:13:13 +0000
From: William D Clinger <email@example.com>
It appears to me that, in order to satisfy Gerry, a compiler must
treat all variables as if they were (pardon the expression) VOLATILE.
This is a considerable price to pay for an abstraction-breaking
facility that not even Gerry is likely to use very often.
Whoa! We seem to be confusing the existence of opacity in a language
with procedures necessarily being opaque in that language.
I would like to have an opaque data type; I would also like to have
standard methods for getting arity and other information from
procedures. I have uses for opacity, but closing procedures is not
one of them.
If we make opacity a first-class datatype, then it can be applied when
desired, rather than thrust upon every closure, even when unwanted.
If this is truly what our impasse is about, then a plausable solution
* Let those who desire opacity refine Ziggy's proposal.
* Let those who advocate translucent procedures propose constructs to
enable such access.
Scheme would attain a large step in utility if we could adopt both