If you read the error, you get the explanation.
There is no applicable method for the generic function
#<STANDARD-GENERIC-FUNCTION A (1)>
when called with arguments
(B).
So you got a call, which is similar to (a 'b)
. But b
is a symbol, not a CLOS instance.
(b c)
is a list of two symbols. You probably wanted to create a list of two CLOS instances. Use LIST
to create a list with evaluated arguments.