primitive-generics are limited in their arities

[Andy Wingo]

Hey goops hackers,

I've run into an irritating little bug in primitive-generics where they
are limited to a specific arity. Here's a little example.

guile> (use-modules (oop goops))
guile> (define-method (write (foo <list>) (bar <list>) (baz <list>))
... (display (list foo bar baz))(newline))
guile> (write '(4 5 6) '(6 7) '(5 6))
 
Backtrace:
In current input:
   4: 0* [write (4 5 6) (6 7) (5 6)]
 
<unnamed port>:4:1: In procedure write in expression (write (quote #)
(quote #) ...):
<unnamed port>:4:1: Wrong number of arguments to #<primitive-generic
write>
ABORT: (wrong-number-of-args)
guile> write
$1 = #<primitive-generic write>
guile> (primitive-generic-generic write)
$2 = #<<generic> write (7)>
guile> ($2 '(4 5 6) '(6 7) '(5 6))
((4 5 6) (6 7) (5 6))

I wonder if this is a problem with the primitive-generic support or if
there's something that I'm doing wrong. It seems unnatural to have to

        (define-method write ...) 

and then

        (set! write (primitive-generic-generic write))

I tried to look into a fix but I got lost. What's the word on this?

Thanks for the help,

wingo.