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Proposal for EVAL
It seems to me that Jinx's proposal DOES contain the notion of "first-class"
environments. The procedures NULL-ENVIRONMENT, INTERACTION-ENVIRONMENT,
and SCHEME-REPORT-ENVIRONMENT return a value that can be used like any
other value. Granted, the proposal only specifies 3 possible environments
and no specific operations on environments other than EVAL. A better
wording would probably be: "weak" first-class environments. Anyway, this
is just a detail.
To better evaluate this proposal I think it would be good to have an
idea how it could be extended to "stronger" first-class environments
and how it interacts with other language features (current or
reasonable extensions). For example, packages, macros and error
systems. In particular, what are the MIT-Scheme extensions to this
proposal? Also, what syntactic environment is used during evaluation?
I am not judging the proposal at this point (or Jinx's intensions :-),
I just want to have a better feel for the ramifications. It would be
unfortunate if EVAL dirtied the rest of the language (and once again,
I'm not saying the current proposal does).