Features

[Michael Greenwald <Greenwald@STONY-BROOK.SCRC.Symbolics.COM>]

    Date: Wed, 18 May 88 20:58 CDT
    From: David Vinayak Wallace <Gumby@MCC.COM>

	Date: Tue, 10 May 88 14:02:42 PDT
	From: Jon L White <edsel!jonl@labrea.stanford.edu>

	X3J13 is considering a proposal to require the setting of *package* to be
	the KEYWORD package during the scope of reading the forms under a #+ or a 
	#-.  This will tend to give the appearance of "namestring" comparison rather
	than EQ only because, for example,  #+LUCID  will be read in the feature as
	:LUCID, and the search on *features* will be for that symbol.  The X3J13 
	proposal would permit reading in feature names like #+MACSYMA:HYPERLINEAR,
	in which case the member test would be with the symbol MACSYMA:HYPERLINEAR.

    What do you do if you encounter #+nasa:hyperdrive but you don't have the
    nasa package defined?

The Symbolics' reader allows the use of package qualified symbols for
features.  If no package is present the symbol is assumed to be in the
keyword package.  If a symbol is in an undefined package then the
feature is considered "not present", so #- is true, and #+ is false.