Following is a list of all known incompatibilities between this package and Common Lisp as documented in Steele (2nd edition).
Certain function names, such as member,
assoc, and floor, were already taken by
(incompatible) Emacs Lisp functions; this package appends
‘*’ to the
names of its Common Lisp versions of these functions.
The word defun* is required instead of
defun in order to use extended Common Lisp argument
lists in a function. Likewise, defmacro* and
function* are versions of those forms which
understand full-featured argument lists. The
&whole keyword does not work in
defmacro argument lists (except inside recursive
argument lists).
The equal predicate does not distinguish between
IEEE floating-point plus and minus zero. The equalp
predicate has several differences with Common Lisp; see Predicates.
The setf mechanism is entirely compatible, except
that setf-methods return a list of five values rather than five
values directly. Also, the new “setf
function” concept (typified by (defun (setf foo)
...)) is not implemented.
The do-all-symbols form is the same as
do-symbols with no obarray argument. In
Common Lisp, this form would iterate over all symbols in all
packages. Since Emacs obarrays are not a first-class package
mechanism, there is no way for do-all-symbols to
locate any but the default obarray.
The loop macro is complete except that
loop-finish and type specifiers are
unimplemented.
The multiple-value return facility treats lists as multiple
values, since Emacs Lisp cannot support multiple return values
directly. The macros will be compatible with Common Lisp if
values or values-list is always used to
return to a multiple-value-bind or other
multiple-value receiver; if values is used without
multiple-value-... or vice-versa the effect will be
different from Common Lisp.
Many Common Lisp declarations are ignored, and others match
the Common Lisp standard in concept but not in detail. For
example, local special declarations, which are
purely advisory in Emacs Lisp, do not rigorously obey the scoping
rules set down in Steele's book.
The variable *gensym-counter* starts out with a
pseudo-random value rather than with zero. This is to cope with
the fact that generated symbols become interned when they are
written to and loaded back from a file.
The defstruct facility is compatible, except that
structures are of type :type vector :named by
default rather than some special, distinct type. Also, the
:type slot option is ignored.
The second argument of check-type is treated
differently.