[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Proposal for EVAL
In your letter dated Wed, 20 May 92 10:22:33 EDT, Mark Feeley wrote:
>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.
I may be wrong, but if the result of (INTERACTION-ENVIRONMENT)
can be taken to another environment and still mean the environment
where (INTERACTION-ENVIRONMENT) was evaluated (this was not clear to me in
the original proposal, which I have unfortunately lost),
there is surely nothing "weak" about these environments?
Of course, it is always possible to add power (e.g. ADD-BINDING! might add
a binding, not by creating a sub-environment but by extending the current
one), but they seem quite powerful as they are.
If I remember well, INTERACTION-ENVIRONMENT wasn't supposed to be essential,
I suppose for this reason.
P.S.: If INTERACTION-ENVIRONMENT didn't mean to mean the current
environment I have misremembered. It that case I beg your pardon.