Re: Fixing null-environment and scheme-report-environment

[Richard Kelsey <kelsey@research.nj.nec.com>]

   From: Kent Pitman <kmp@harlequin.com>
   Date: Tue, 17 Feb 98 15:48:50 EST

   Further, the phrase "only the set of bindings specified in the corresponding
   report that the implementation supports" has two parses, at least one of which
   is NOT what you want and needs to be fixed in any case.  (It appears to say
   that you are allowed to support only a subset and that this will magically
   reveal the subset.)

You are allowed to support only a subset.  Some of the bindings
are optional, and an implementation may or may not support them.
The intent is that SCHEME-REPORT-ENVIRONMENT include all of the
required bindings plus whichever of the optional bindings the
implementation supports, and nothing else.

How about:

 SCHEME-REPORT-ENVIRONMENT returns a specifier for an environment
 that contains the required bindings defined in the specified report,
 all of the optional bindings from that report that the implementation
 supports, and no others.

 NULL-ENVIRONMENT returns a specifier for an environment that contains
 the (syntactic) bindings for the required syntactic keywords defined
 in the specified report, the (syntactic) bindings for all optional
 keywords from that report that the implementation supports, and no
 others.