alan@allegra.UUCP (06/07/84)
[Warning: Don't read this line.] We're running Franz Lisp under 4.2 BSD. I'm having a problem compiling functions with optional arguments. This code works correctly when interpreted: (defun f (&optional x &optional y) (cons x y)) When compiled, liszt gives the following error message: ?Error: test.l: f: illegal form in lambda list (&optional y) ?Error: test.l: : Compilation aborted due to previous errors Has anyone else run into this compiler bug? -- Alan S. Driscoll AT&T Bell Laboratories
broome@brl-tgr.UUCP (06/07/84)
Re: (defun f (&optional x &optional y) (cons x y)) Is the '&' doing something special? The function compiles and runs correctly without the '&' under version 8.36 of Liszt and Opus 38.79 of Franz. Paul Broome broome@brl-tgr
barmar@mit-eddie.UUCP (Barry Margolin) (06/08/84)
-------------------- (defun f (&optional x &optional y) (cons x y)) -------------------- I don't know Franz Lisp, but in Maclisp and Zetalisp, everything following &optional is optional, which means the second &optional is redundant, and this is probably the cause for the error. -- Barry Margolin ARPA: barmar@MIT-Multics UUCP: ..!genrad!mit-eddie!barmar
chris@umcp-cs.UUCP (06/08/84)
As I understand it [and I only dabble in Franz occasionally so don't
take this TOO seriously],
(defun f (&optional ...
makes some optional arguments, with [again optional] default values
if said optional arguments are not passed.
(defun f (&optional (x nil) (y 'foo)) ...
should make ``x'' bound to the first argument if any, nil if none,
and ``y'' bound to the second argument if any, or 'foo if none.
[It may also be written as ``(&optional x (y 'foo))''.]
As far as I know, &optional must come after all the non-optional
arguments, not be used twice, and not be used in conjunction with
&rest.
--
In-Real-Life: Chris Torek, Univ of MD Comp Sci (301) 454-7690
UUCP: {seismo,allegra,brl-bmd}!umcp-cs!chris
CSNet: chris@umcp-cs ARPA: chris@maryland