Issue: PATHNAME-EXTENSIONS (Version 1)

[Jim McDonald <jlm@lucid.com>]

Does this really need to be a part of the standard?  Why can't it
just be privately distributed (or re-invented) by the few sites that
want it?  As far as I can see, it is merely a syntax checker which
sits entirely on top of the current language, and anyone who cares
can implement it quickly after reading the standard.

If one is to persue portability in this fashion, I think it would be
more elegant to seriously implement the COMMON data type and have a
pair of predicates that tested any given lisp form and said whether it
was data (or code) that adhered to the common lisp standard.  (The
data predicate might itself be written portably.  The code predicate
would need to be ported to each vendor to detect supported but
non-standard features, since (TRICKY X) would be standard if TRICKY
were user-defined, but would not be if it implemented some
vendor-specific magic.)  Given such predicates you could safely
descend through any lisp structure, using the predicates to warn you
of pitfalls ahead.   

Doing bits and pieces of syntax checking seems somewhat ad hoc, unless
the claim is that pathnames are and will be the only "standard" data
which have unpredictable format.

  jlm